12583 + Mcqs in Physics Page 205 McqOptions

10201.	Assertion : The average and instantaneous velocities have same value in a uniform motion. Reason : In uniform motion, the velocity of an object increases uniformly.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» D. If the assertion and reason both are false.

Discussion

10202.	Assertion : In the process of photoelectric emission, all the emitted photoelectrons have the same kinetic energy. Reason : The photon transfers its whole energy to the electron of the atom in photoelectric effect.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» F.

Discussion

10203.	The magnetic field near a current carrying conductor is given by [Orissa JEE 2003]
A.	Coulomb?s law
B.	Lenz? law
C.	Biot-savart?s law
D.	Kirchoff?s law
Answer» D. Kirchoff?s law

Discussion

10204.	Gases begin to conduct electricity at low pressure because [CBSE PMT 1994]
A.	At low pressure, gases turn to plasma
B.	Colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms
C.	Atoms break up into electrons and protons
D.	The electrons in atoms can move freely at low pressure
Answer» C. Atoms break up into electrons and protons

Discussion

10205.	As shown in the figure, a very thin sheet of aluminium is placed in between the plates of the condenser. Then the capacity [AIEEE 2003]
A.	Will increase
B.	Will decrease
C.	Remains unchanged
D.	May increase or decrease
Answer» D. May increase or decrease

Discussion

10206.	A gas is suddenly compressed to one fourth of its original volume. What will be its final pressure, if its initial pressure is P [Pb. PET 2002]
A.	Lesss than P
B.	More than P
C.	P
D.	Either (a) or (c)
Answer» C. P

Discussion

10207.	An unknown frequency x produces 8 beats per seconds with a frequency of 250 Hz and 12 beats with 270 Hz source, then x is [CPMT 1997; KCET 2000]
A.	258 Hz
B.	242 Hz
C.	262 Hz
D.	282 Hz
Answer» B. 242 Hz

Discussion

10208.	The magnetic induction at the centre of a current carrying circular of coil radius r, is [J & K CET 2004]
A.	Directly proportional to r
B.	Inversely proportional r
C.	Directly proportional to r2
D.	Inversely proportional to r2
Answer» C. Directly proportional to r2

Discussion

10209.	Masses of two substances are 1 g and 9 g respectively. If their kinetic energies are same, then the ratio of their momentum will be [BHU 2004]
A.	1 : 9
B.	9 : 1
C.	3 : 1
D.	1 : 3
Answer» E.

Discussion

10210.	The magnetic induction in air at a point 1cm away from a long wire that carries a current of 1A, will be [BHU 1999]
A.	\[1\times {{10}^{-5}}T\]
B.	\[2\times {{10}^{-5}}T\]
C.	\[3\times {{10}^{-5}}T\]
D.	\[4\times {{10}^{-5}}T\]
Answer» C. \[3\times {{10}^{-5}}T\]

Discussion

10211.	An ac circuit consists of an inductor of inductance 0.5 H and a capacitor of capacitance 8 mF in series. The current in the circuit is maximum when the angular frequency of ac source is [CPMT 1986]
A.	500 rad/sec
B.	2 ´ 105 rad/sec
C.	4000 rad/sec
D.	5000 rad/sec
Answer» B. 2 ´ 105 rad/sec

Discussion

10212.	Current in the circuit is wattless, if
A.	Inductance in the circuit is zero
B.	Resistance in the circuit is zero
C.	Current is alternating
D.	Resistance and inductance both are zero
Answer» C. Current is alternating

Discussion

10213.	Assertion : Young?s modulus for a perfectly plastic body is zero. Reason : For a perfectly plastic body, restoring force is zero.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

10214.	The capacitance of a spherical condenser is \[1\mu F\]. If the spacing between the two spheres is\[1\,mm\], then the radius of the outer sphere is [CPMT 1989]
A.	\[30cm\]
B.	\[6m\]
C.	\[5cm\]
D.	\[3m\]
Answer» E.

Discussion

10215.	While tuning in a certain broadcast station with a receiver, we are actually
A.	Varying the local oscillator frequency
B.	Varying the frequency of the radio signal to be picked up
C.	Tuning the antenna
D.	None of these
Answer» B. Varying the frequency of the radio signal to be picked up

Discussion

10216.	1 g of a steam at 100°C melt how much ice at 0°C? (Latent heat of ice = 80 cal/gm and latent heat of steam = 540 cal/gm) [Pb. PET 2000]
A.	1 gm
B.	2 gm
C.	4 gm
D.	8 gm
Answer» E.

Discussion

10217.	Assertion : The work done during a round trip is always zero. Reason : No force is required to move a body in its round trip.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

10218.	Assertion : Isobars are the element having same mass number but different atomic number. Reason : Neutrons and protons are present inside nucleus. [AIIMS 1997]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» C. If assertion is true but reason is false.

Discussion

10219.	Power delivered by the source of the circuit becomes maximum, when [DCE 2004]
A.	\[\omega L=\omega C\]
B.	\[\omega L=\frac{1}{\omega C}\]
C.	\[\omega L=-\,{{\left( \frac{1}{\omega C} \right)}^{2}}\]
D.	\[\omega L=\sqrt{\omega C}\]
Answer» C. \[\omega L=-\,{{\left( \frac{1}{\omega C} \right)}^{2}}\]

Discussion

10220.	If the binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of \[L{{i}^{++}}\] is [AIEEE 2003]
A.	122.4 eV
B.	30.6 eV
C.	13.6 eV
D.	3.4 eV
Answer» C. 13.6 eV

Discussion

10221.	How much current should be passed through acidified water for 100 s to liberate 0.224 litre of \[{{H}_{2}}\] [DCE 2002]
A.	22.4 A
B.	\[19.3\,\,A\]
C.	9.65 A
D.	1 A
Answer» C. 9.65 A

Discussion

10222.	Assertion : Owls can move freely during night. Reason : They have large number of rods on their retina. [AIIMS 2003]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» D. If the assertion and reason both are false.

Discussion

10223.	Assertion : Water flows faster than honey. Reason : The coefficient of viscosity of water is less than honey.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

10224.	Two spherical conductors B and C having equal radii and carrying equal charges in them repel each other with a force F when kept apart at some distance. A third spherical conductor having same radius as that of B but uncharged is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is [AIEEE 2004]
A.	\[F/4\]
B.	\[3F/4\]
C.	\[F/8\]
D.	\[3F/8\]
Answer» E.

Discussion

10225.	A body of mass 2 kg is thrown up vertically with K.E. of 490 joules. If the acceleration due to gravity is 9.8\[m/{{s}^{2}}\], then the height at which the K.E. of the body becomes half its original value is given by [EAMCET 1986]
A.	50 m
B.	12.5 m
C.	25 m
D.	10 m
Answer» C. 25 m

Discussion

10226.	Assertion : In high latitude one sees colourful curtains of light hanging down from high altitudes. Reason : The high energy charged particles from the sun are deflected to polar regions by the magnetic field of the earth. [AIIMS 2003]
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

10227.	A rope of length 5m is kept on frictionless surface and a force of 5N is applied to one of its end. Find tension in the rope at 1m from this end [RPET 2000]
A.	1 N
B.	3 N
C.	4 N
D.	5 N
Answer» D. 5 N

Discussion

10228.	The r.m.s. voltage of domestic electricity supply is 220 volt . Electrical appliances should be designed to withstand an instantaneous voltage of
A.	220 V
B.	310 V
C.	330 V
D.	440 V
Answer» C. 330 V

Discussion

10229.	Assertion : Gravitational potential of earth at every place on it is negative. Reason : Every body on earth is bound by the attraction of earth.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

10230.	Water falls from a height of 210m. Assuming whole of energy due to fall is converted into heat the rise in temperature of water would be (J = 4.3 Joule/cal) [Pb. PMT 2002]
A.	42°C
B.	49°C
C.	0.49°C
D.	4.9°C
Answer» D. 4.9°C

Discussion

10231.	When subjected to a transverse electric field, cathode rays move [MP PET 1994]
A.	Down the potential gradient
B.	Up the potential gradient
C.	Along a hyperbolic path
D.	Along a circular path
Answer» C. Along a hyperbolic path

Discussion

10232.	The speed of a wave in a certain medium is 960 m/s. If 3600 waves pass over a certain point of the medium in 1 minute, the wavelength is [MP PMT 2000]
A.	2 metres
B.	4 metres
C.	8 metres
D.	16 metres
Answer» E.

Discussion

10233.	Assertion : Multiplying any vector by an scalar is a meaningful operations. Reason : In uniform motion speed remains constant.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» C. If assertion is true but reason is false.

Discussion

10234.	In a current carrying long solenoid, the field produced does not depend upon [MP PET 1999]
A.	Number of turns per unit length
B.	Current flowing
C.	Radius of the solenoid
D.	All of the above three
Answer» D. All of the above three

Discussion

10235.	Assertion : The blood pressure in humans is greater at the feet than at the brain. Reason : Pressure of liquid at any point is proportional to height, density of liquid and acceleration due to gravity.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

10236.	A resistance of 20 ohms is connected to a source of an alternating potential \[V=220\sin (100\pi t)\]. The time taken by the current to change from its peak value to r.m.s value is [MP PET 2001]
A.	0.2 sec
B.	0.25 sec
C.	\[25\times {{10}^{-3}}\]sec
D.	\[2.5\times {{10}^{-3}}\]sec
Answer» E.

Discussion

10237.	The isothermal bulk modulus of a gas at atmospheric pressure is [AIIMS 2000; KCET 1999; Pb. PMT 2003]
A.	\[1\,mm\]of Hg
B.	\[13.6\,mm\]of Hg
C.	\[1.013\times {{10}^{5}}\,N/{{m}^{2}}\]
D.	\[2.026\times {{10}^{5}}N/{{m}^{2}}\]
Answer» D. \[2.026\times {{10}^{5}}N/{{m}^{2}}\]

Discussion

10238.	The magnitude of vector \[\overrightarrow{A},\,\overrightarrow{B}\] and \[\overrightarrow{C}\] are respectively 12, 5 and 13 units and \[\overrightarrow{A}+\overrightarrow{B}=\overrightarrow{C}\] then the angle between \[\overrightarrow{A}\] and \[\overrightarrow{B}\] is [CPMT 1997]
A.	0
B.	\[\pi \]
C.	\[\pi /2\]
D.	\[\pi /4\]
Answer» D. \[\pi /4\]

Discussion

10239.	Assertion : An electric lamp connected in series with a variable capacitor and ac source, its brightness increases with increase in capacitance. Reason : Capacitive reactance decrease with increase in capacitance of capacitor.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

10240.	Assertion : The size of the mirror affect the nature of the image. Reason : Small mirrors always forms a virtual image.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» E. If assertion is false but reason is true.

Discussion

10241.	Assertion : The mirrors used in search lights are parabolic and not concave spherical. Reason : In a concave spherical mirror the image formed is always virtual.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» D. If the assertion and reason both are false.

Discussion

10242.	Assertion : Just before setting, the sun may appear to be elliptical. This happens due to refraction. Reason : Refraction of light ray through the atmosphere may cause different magnification in mutually perpendicular directions.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

10243.	A hospital uses an ultrasonic scanner to locate tumours in a tissue. The operating frequency of the scanner is 4.2 MHz\[.\] The speed of sound in a tissue is 1.7 km-s?1. The wavelength of sound in the tissue is close to [CBSE PMT 1995]
A.	\[4\times {{10}^{-4}}\,m\]
B.	\[8\times {{10}^{-3}}\,m\]
C.	\[4\times {{10}^{-3}}\,m\]
D.	\[8\times {{10}^{-4}}\,m\]
Answer» B. \[8\times {{10}^{-3}}\,m\]

Discussion

10244.	Which of the following statement is incorrect
A.	Both ac and dc dynamo have a field magnet
B.	Both ac and dc dynamo have an armature
C.	Both ac and dc dynamo convert mechanical energy into electrical energy
D.	Both ac and dc dynamo have slip rings
Answer» E.

Discussion

10245.	If a lighter body (mass \[{{M}_{1}}\] and velocity \[{{V}_{1}}\]) and a heavier body (mass \[{{M}_{2}}\] and velocity \[{{V}_{2}}\]) have the same kinetic energy, then [MP PMT 1997]
A.	\[{{M}_{2}}{{V}_{2}}<{{M}_{1}}{{V}_{1}}\]
B.	\[{{M}_{2}}{{V}_{2}}={{M}_{1}}{{V}_{1}}\]
C.	\[{{M}_{2}}{{V}_{1}}={{M}_{1}}{{V}_{2}}\]
D.	\[{{M}_{2}}{{V}_{2}}>{{M}_{1}}{{V}_{1}}\]
Answer» E.

Discussion

10246.	In Bohr model of hydrogen atom, the ratio of periods of revolution of an electron in \[n=2\] and \[n=1\] orbits is [EAMCET (Engg.) 2000]
A.	2 : 1
B.	4 : 1
C.	8 : 1
D.	16 : 1
Answer» D. 16 : 1

Discussion

10247.	The liquid meniscus in capillary tube will be convex, if the angle of contact is [EAMCET (Med.) 1995; KCET 2001; Pb. PET 2000]
A.	Greater than \[90{}^\circ \]
B.	Less than \[90{}^\circ \]
C.	Equal to \[90{}^\circ \]
D.	Equal to\[{{0}^{o}}\]
Answer» B. Less than \[90{}^\circ \]

Discussion

10248.	Assertion : The ion cannot move with a speed beyond a certain limit in a cyclotron. Reason : As velocity increases time taken by ion increases.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» D. If the assertion and reason both are false.

Discussion

10249.	The coils of a step down transformer have 500 and 5000 turns. In the primary coil an ac of 4 ampere at 2200 volts is sent. The value of the current and potential difference in the secondary coil will be [MP PET 1996]
A.	20 A, 220 V
B.	0.4 A, 22000 V
C.	40 A, 220 V
D.	40 A, 22000 V
Answer» D. 40 A, 22000 V

Discussion

10250.	Assertion : The concept of surface tension is held only for liquids. Reason : Surface tension does not hold for gases.
A.	If both assertion and reason are true and the reason is the correct explanation of the assertion.
B.	If both assertion and reason are true but reason is not the correct explanation of the assertion.
C.	If assertion is true but reason is false.
D.	If the assertion and reason both are false.
E.	If assertion is false but reason is true.
Answer» C. If assertion is true but reason is false.

Discussion

Explore topic-wise MCQs in Joint Entrance Exam - Main (JEE Main).

Assertion : The average and instantaneous velocities have same value in a uniform motion. Reason : In uniform motion, the velocity of an object increases uniformly.

Assertion : In the process of photoelectric emission, all the emitted photoelectrons have the same kinetic energy. Reason : The photon transfers its whole energy to the electron of the atom in photoelectric effect.

The magnetic field near a current carrying conductor is given by [Orissa JEE 2003]

Gases begin to conduct electricity at low pressure because [CBSE PMT 1994]

As shown in the figure, a very thin sheet of aluminium is placed in between the plates of the condenser. Then the capacity [AIEEE 2003]

A gas is suddenly compressed to one fourth of its original volume. What will be its final pressure, if its initial pressure is P [Pb. PET 2002]

An unknown frequency x produces 8 beats per seconds with a frequency of 250 Hz and 12 beats with 270 Hz source, then x is [CPMT 1997; KCET 2000]

The magnetic induction at the centre of a current carrying circular of coil radius r, is [J & K CET 2004]

Masses of two substances are 1 g and 9 g respectively. If their kinetic energies are same, then the ratio of their momentum will be [BHU 2004]

The magnetic induction in air at a point 1cm away from a long wire that carries a current of 1A, will be [BHU 1999]

An ac circuit consists of an inductor of inductance 0.5 H and a capacitor of capacitance 8 mF in series. The current in the circuit is maximum when the angular frequency of ac source is [CPMT 1986]

Current in the circuit is wattless, if

Assertion : Young?s modulus for a perfectly plastic body is zero. Reason : For a perfectly plastic body, restoring force is zero.

The capacitance of a spherical condenser is \[1\mu F\]. If the spacing between the two spheres is\[1\,mm\], then the radius of the outer sphere is [CPMT 1989]

While tuning in a certain broadcast station with a receiver, we are actually

1 g of a steam at 100°C melt how much ice at 0°C? (Latent heat of ice = 80 cal/gm and latent heat of steam = 540 cal/gm) [Pb. PET 2000]

Assertion : The work done during a round trip is always zero. Reason : No force is required to move a body in its round trip.

Assertion : Isobars are the element having same mass number but different atomic number. Reason : Neutrons and protons are present inside nucleus. [AIIMS 1997]

Power delivered by the source of the circuit becomes maximum, when [DCE 2004]

If the binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of \[L{{i}^{++}}\] is [AIEEE 2003]

How much current should be passed through acidified water for 100 s to liberate 0.224 litre of \[{{H}_{2}}\] [DCE 2002]

Assertion : Owls can move freely during night. Reason : They have large number of rods on their retina. [AIIMS 2003]

Assertion : Water flows faster than honey. Reason : The coefficient of viscosity of water is less than honey.

A body of mass 2 kg is thrown up vertically with K.E. of 490 joules. If the acceleration due to gravity is 9.8\[m/{{s}^{2}}\], then the height at which the K.E. of the body becomes half its original value is given by [EAMCET 1986]

Assertion : In high latitude one sees colourful curtains of light hanging down from high altitudes. Reason : The high energy charged particles from the sun are deflected to polar regions by the magnetic field of the earth. [AIIMS 2003]

A rope of length 5m is kept on frictionless surface and a force of 5N is applied to one of its end. Find tension in the rope at 1m from this end [RPET 2000]

The r.m.s. voltage of domestic electricity supply is 220 volt . Electrical appliances should be designed to withstand an instantaneous voltage of

Assertion : Gravitational potential of earth at every place on it is negative. Reason : Every body on earth is bound by the attraction of earth.

Water falls from a height of 210m. Assuming whole of energy due to fall is converted into heat the rise in temperature of water would be (J = 4.3 Joule/cal) [Pb. PMT 2002]

When subjected to a transverse electric field, cathode rays move [MP PET 1994]

The speed of a wave in a certain medium is 960 m/s. If 3600 waves pass over a certain point of the medium in 1 minute, the wavelength is [MP PMT 2000]

Assertion : Multiplying any vector by an scalar is a meaningful operations. Reason : In uniform motion speed remains constant.

In a current carrying long solenoid, the field produced does not depend upon [MP PET 1999]

Assertion : The blood pressure in humans is greater at the feet than at the brain. Reason : Pressure of liquid at any point is proportional to height, density of liquid and acceleration due to gravity.

A resistance of 20 ohms is connected to a source of an alternating potential \[V=220\sin (100\pi t)\]. The time taken by the current to change from its peak value to r.m.s value is [MP PET 2001]

The isothermal bulk modulus of a gas at atmospheric pressure is [AIIMS 2000; KCET 1999; Pb. PMT 2003]

The magnitude of vector \[\overrightarrow{A},\,\overrightarrow{B}\] and \[\overrightarrow{C}\] are respectively 12, 5 and 13 units and \[\overrightarrow{A}+\overrightarrow{B}=\overrightarrow{C}\] then the angle between \[\overrightarrow{A}\] and \[\overrightarrow{B}\] is [CPMT 1997]

Assertion : An electric lamp connected in series with a variable capacitor and ac source, its brightness increases with increase in capacitance. Reason : Capacitive reactance decrease with increase in capacitance of capacitor.

Assertion : The size of the mirror affect the nature of the image. Reason : Small mirrors always forms a virtual image.

Assertion : The mirrors used in search lights are parabolic and not concave spherical. Reason : In a concave spherical mirror the image formed is always virtual.

Assertion : Just before setting, the sun may appear to be elliptical. This happens due to refraction. Reason : Refraction of light ray through the atmosphere may cause different magnification in mutually perpendicular directions.

A hospital uses an ultrasonic scanner to locate tumours in a tissue. The operating frequency of the scanner is 4.2 MHz\[.\] The speed of sound in a tissue is 1.7 km-s?1. The wavelength of sound in the tissue is close to [CBSE PMT 1995]

Which of the following statement is incorrect

If a lighter body (mass \[{{M}_{1}}\] and velocity \[{{V}_{1}}\]) and a heavier body (mass \[{{M}_{2}}\] and velocity \[{{V}_{2}}\]) have the same kinetic energy, then [MP PMT 1997]

In Bohr model of hydrogen atom, the ratio of periods of revolution of an electron in \[n=2\] and \[n=1\] orbits is [EAMCET (Engg.) 2000]

The liquid meniscus in capillary tube will be convex, if the angle of contact is [EAMCET (Med.) 1995; KCET 2001; Pb. PET 2000]

Assertion : The ion cannot move with a speed beyond a certain limit in a cyclotron. Reason : As velocity increases time taken by ion increases.

The coils of a step down transformer have 500 and 5000 turns. In the primary coil an ac of 4 ampere at 2200 volts is sent. The value of the current and potential difference in the secondary coil will be [MP PET 1996]

Assertion : The concept of surface tension is held only for liquids. Reason : Surface tension does not hold for gases.