12583 + Mcqs in Physics Page 200 McqOptions

9951.	Water rises in a capillary tube to a certain height such that the upward force due to surface tension is balanced by \[75\times {{10}^{-4}}N\] force due to the weight of the liquid. If the surface tension of water is \[6\times {{10}^{-2}}\,N{{m}^{-1}}\], the inner circumference of the capillary must be [CPMT 1988, 86]
A.	\[1.25\times {{10}^{-2}}m\]
B.	\[0.50\times {{10}^{-2}}m\]
C.	\[6.5\times {{10}^{-2}}m\]
D.	\[12.5\times {{10}^{-2}}m\]
Answer» E.

Discussion

9952.	The unit of electric permittivity is [MP PET 2003]
A.	\[Volt/{{m}^{2}}\]
B.	Joule/coulomb
C.	Farad/m
D.	Henry/m
Answer» D. Henry/m

Discussion

9953.	Ultrasonic signal sent from SONAR returns to it after reflection from a rock after a lapse of 1 sec. If the velocity of ultrasound in water is 1600 ms?1, the depth of the rock in water is [JIPMER 2000]
A.	300 m
B.	400 m
C.	500 m
D.	800 m
Answer» E.

Discussion

9954.	An observer standing near the sea shore observes 54 waves per minute. If the wavelength of the water wave is 10m then the velocity of water wave is [Kerala (Engg.) 2005]
A.	540 ms-1
B.	5.4 ms-1
C.	0.184 ms-1
D.	9 ms-1
Answer» E.

Discussion

9955.	When air in a capacitor is replaced by a medium of dielectric constant K, the capacity [NCERT 1990; CPMT 1972, 82, 90; MP PMT 1993; MP PET 1994; KCET 1994]
A.	Decreases K times
B.	Increases K times
C.	Increases \[{{K}^{2}}\]times
D.	Remains constant
Answer» C. Increases \[{{K}^{2}}\]times

Discussion

9956.	In a circuit, the value of the alternating current is measured by hot wire ammeter as 10 ampere. Its peak value will be [MP PET 1996; AMU (Med.) 1999; KCET (Engg./Med.) 2000; CPMT 2003]
A.	10 A
B.	20 A
C.	14.14 A
D.	7.07 A
Answer» D. 7.07 A

Discussion

9957.	A metallic sheet is inserted between the plates of a parallel plate capacitor. The capacitance of the capacitor [Roorkee 2000]
A.	Increases
B.	Is independent of the position of the sheet
C.	Is maximum when the metal sheet in the middle
D.	Is maximum when the metal sheet touches one of the capacitor plates
Answer» C. Is maximum when the metal sheet in the middle

Discussion

9958.	Assertion : A beaker is completely filled with water at 4°C. It will overflow, both when heated or cooled. Reason : There is expansion of water below and above 4°C.
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

9959.	One mole of an ideal gas with \[\gamma =1.4\], is adiabatically compressed so that its temperature rises from 27°C to 35°C. The change in the internal energy of the gas is \[(R=8.3\,J/mol.K)\] [EAMCET 2001]
A.	?166 J
B.	166 J
C.	?168 J
D.	168 J
Answer» C. ?168 J

Discussion

9960.	If the change in the value of ?g? at a height h above the surface of the earth is the same as at a depth x below it, then (both x and h being much smaller than the radius of the earth) [NCERT 1983; BHU 2002]
A.	\[x=h\]
B.	\[x=2h\]
C.	\[x=\frac{h}{2}\]
D.	\[x={{h}^{2}}\]
Answer» C. \[x=\frac{h}{2}\]

Discussion

9961.	Equal charges \[q\] are placed at the four corners \[A,\,B,\,C,\,D\] of a square of length \[a\]. The magnitude of the force on the charge at B will be [MP PMT 1994; DPMT 2001]
A.	\[\frac{3{{q}^{2}}}{4\pi {{\varepsilon }_{0}}{{a}^{2}}}\]
B.	\[\frac{4{{q}^{2}}}{4\pi {{\varepsilon }_{0}}{{a}^{2}}}\]
C.	\[\left( \frac{1+2\sqrt{2}}{2} \right)\frac{{{q}^{2}}}{4\pi {{\varepsilon }_{0}}{{a}^{2}}}\]
D.	\[\left( 2+\frac{1}{\sqrt{2}} \right)\frac{{{q}^{2}}}{4\pi {{\varepsilon }_{0}}{{a}^{2}}}\]
Answer» E.

Discussion

9962.	An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The coulomb force \[\overrightarrow{F}\] between the two is (Where \[K=\frac{1}{4\pi {{\varepsilon }_{0}}}\]) [CBSE PMT 2003]
A.	\[-K\frac{{{e}^{2}}}{{{r}^{3}}}\hat{r}\]
B.	\[K\frac{{{e}^{2}}}{{{r}^{3}}}\vec{r}\]
C.	\[-K\frac{{{e}^{2}}}{{{r}^{3}}}\vec{r}\]
D.	\[K\frac{{{e}^{2}}}{{{r}^{2}}}\hat{r}\]
Answer» D. \[K\frac{{{e}^{2}}}{{{r}^{2}}}\hat{r}\]

Discussion

9963.	Assertion : The specific charge for positive rays is a characteristic constant. Reason : The specific charge depends on charge and mass of positive ions present in positive rays.
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

9964.	The specific charge of an electron is [MP PMT/PET 1998; J&K CET 2004; Pb. PET 2002; MH CET 1999]
A.	\[1.6\times {{10}^{-19}}coulomb\]
B.	\[4.8\times {{10}^{-10}}stat\ coulomb\]
C.	\[1.76\times {{10}^{11}}coulomb/kg\]
D.	\[\|8\|\times {{10}^{-15}}Hz\]
Answer» D. \[\|8\|\times {{10}^{-15}}Hz\]

Discussion

9965.	Energy of the electron in nth orbit of hydrogen atom is given by \[{{E}_{n}}=-\frac{13.6}{{{n}^{2}}}eV\]. The amount of energy needed to transfer electron from first orbit to third orbit is [MH CET 2002; Kerala PMT 2002]
A.	13.6 eV
B.	3.4 eV
C.	12.09 eV
D.	1.51 eV
Answer» D. 1.51 eV

Discussion

9966.	A bullet is fired from a rifle. If the rifle recoils freely, then the kinetic energy of the rifle is [AIIMS 1998; JIPMER 2001; UPSEAT 2000]
A.	Less than that of the bullet
B.	More than that of the bullet
C.	Same as that of the bullet
D.	Equal or less than that of the bullet
Answer» B. More than that of the bullet

Discussion

9967.	When a certain length of wire is turned into one circular loop, the magnetic induction at the centre of coil due to some current flowing is \[{{B}_{1}}\] If the same wire is turned into three loops to make a circular coil, the magnetic induction at the center of this coil for the same current will be [MP PMT 2002]
A.	\[{{B}_{1}}\]
B.	\[9\,{{B}_{1}}\]
C.	\[3\,{{B}_{1}}\]
D.	\[27\,{{B}_{1}}\]
Answer» C. \[3\,{{B}_{1}}\]

Discussion

9968.	In a transformer, the number of turns in primary and secondary are 500 and 2000 respectively. If current in primary is 48 A, the current in the secondary is [Orissa PMT 2004]
A.	12 A
B.	24 A
C.	48 A
D.	144 A
Answer» B. 24 A

Discussion

9969.	Assertion : Heavy water is used as moderator in nuclear reactor. Reason : Water cool down the fast neutron.
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

9970.	Assertion : Reversible systems are difficult to find in real world. Reason : Most processes are dissipative in nature [AIIMS 2005]
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

9971.	Electric charges of \[1\mu C,\,-1\mu C\] and \[2\mu C\] are placed in air at the corners A, B and C respectively of an equilateral triangle ABC having length of each side 10 cm. The resultant force on the charge at C is [EAMCET (Engg.) 2000]
A.	0.9 N
B.	1.8 N
C.	2.7 N
D.	3.6 N
Answer» C. 2.7 N

Discussion

9972.	Hydrogen atom emits blue light when it changes from n = 4 energy level to the n = 2 level. Which colour of light would the atom emit when it changes from the n = 5 level to the n = 2 level [KCET 1993]
A.	Red
B.	Yellow
C.	Green
D.	Violet
Answer» E.

Discussion

9973.	Which one of the series of hydrogen spectrum is in the visible region [RPMT 1999;MP PET 1990; MP PMT 1994; AFMC 1998; CBSE PMT 1990; MH CET 2004]
A.	Lyman series
B.	Balmer series
C.	Paschen series
D.	Bracket series
Answer» C. Paschen series

Discussion

9974.	Assertion : When capacitive reactance is smaller than the inductive reactance in LCR current, e.m.f. leads the current . Reason : The phase angle is the angle between the alternating e.m.f. and alternating current of the circuit.
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

9975.	The attenuation in optical fibre is mainly due to [AFMC 2003]
A.	Absorption
B.	Scattering
C.	Neither absorption nor scattering
D.	Both (a) and (b)
Answer» E.

Discussion

9976.	Two waves \[y=0.25\sin 316\,t\] and \[y=0.25\sin 310\,t\] are travelling in same direction. The number of beats produced per second will be [CPMT 1993; JIPMER 2000]
A.	6
B.	3
C.	3/p
D.	3p
Answer» D. 3p

Discussion

9977.	The couple of tuning forks produces 2 beats in the time interval of 0.4 seconds. So the beat frequency is [CPMT 1996]
A.	8 Hz
B.	5 Hz
C.	2 Hz
D.	10 Hz
Answer» C. 2 Hz

Discussion

9978.	The wavelength of yellow line of sodium is 5896 Å. Its wave number will be [MP PET 2001]
A.	50883 × 1010 per second
B.	16961 per cm
C.	17581 per cm
D.	50883 per cm
Answer» C. 17581 per cm

Discussion

9979.	As per Bohr model, the minimum energy (in eV) required to remove an electron from the ground state of doubly ionized Li atom (Z = 3) is [IIT 1997 Re-Exam; MH CET 2000]
A.	1.51
B.	13.6
C.	40.8
D.	122.4
Answer» E.

Discussion

9980.	A light bulb, a capacitor and a battery are connected together as shown here, with switch \[S\] initially open. When the switch \[S\]is closed, which one of the following is true [MP PMT 1995]
A.	The bulb will light up for an instant when the capacitor starts charging
B.	The bulb will light up when the capacitor is fully charged
C.	The bulb will not light up at all
D.	The bulb will light up and go off at regular intervals
Answer» B. The bulb will light up when the capacitor is fully charged

Discussion

9981.	The colour of the second line of Balmer series is [J & K CET 2004]
A.	Blue
B.	Yellow
C.	Red
D.	Violet
Answer» B. Yellow

Discussion

9982.	Assertion : It is hotter over the top of a fire than at the same distance on the sides. Reason : Air surrounding the fire conducts more heat upwards. [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

9983.	The first member of the Paschen series in hydrogen spectrum is of wavelength 18,800 Å. The short wavelengths limit of Paschen series is [EAMCET (Med.) 2000]
A.	1215 Å
B.	6560 Å
C.	8225 Å
D.	12850 Å
Answer» D. 12850 Å

Discussion

9984.	\[+2C\] and \[+6C\] two charges are repelling each other with a force of \[12\,N\]. If each charge is given \[-2C\] of charge, then the value of the force will be [CPMT 1979; Kerala PMT 2002]
A.	\[4N\] (Attractive)
B.	\[4N\] (Repulsive)
C.	\[8N\] (Repulsive)
D.	Zero
Answer» E.

Discussion

9985.	A 220 V, 50 Hz ac source is connected to an inductance of 0.2 H and a resistance of 20 ohm in series. What is the current in the circuit [MNR 1998; JIPMER 2001, 02]
A.	10 A
B.	5 A
C.	33.3 A
D.	3.33 A
Answer» E.

Discussion

9986.	In an ac circuit, a resistance of R ohm is connected in series with an inductance L. If phase angle between voltage and current be 45°, the value of inductive reactance will be [MP PMT/PET 1998]
A.	\[\frac{R}{4}\]
B.	\[\frac{R}{2}\]
C.	R
D.	Cannot be found with the given data
Answer» D. Cannot be found with the given data

Discussion

9987.	L, C and R denote inductance, capacitance and resistance respectively. Pick out the combination which does not have the dimensions of frequency [MP PMT 1994]
A.	\[\frac{1}{RC}\]
B.	\[\frac{R}{L}\]
C.	\[\frac{1}{\sqrt{LC}}\]
D.	\[\frac{C}{L}\]
Answer» E.

Discussion

9988.	The acceleration due to gravity at pole and equator can be related as [DPMT 2002]
A.	\[{{g}_{p}}<{{g}_{e}}\]
B.	\[{{g}_{p}}={{g}_{e}}=g\]
C.	\[{{g}_{p}}={{g}_{e}}<g\]
D.	\[{{g}_{p}}>{{g}_{e}}\]
Answer» E.

Discussion

9989.	Assertion : Lenz?s law violates the principle of conservation of energy. Reason : Induced e.m.f., opposes always the change in magnetic flux responsible for its production.
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

9990.	PQRS is a square loop made of uniform conducting wire the current enters the loop at P and leaves at S. Then the magnetic field will be [KCET 2000]
A.	Maximum at the centre of the loop
B.	Zero at the centre of loop
C.	Zero at all points inside the loop
D.	Zero at all points outside of the loop
Answer» C. Zero at all points inside the loop

Discussion

9991.	Assertion : If three capacitors of capacitance \[{{C}_{\text{1}}}
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

9992.	Assertion : A spring has potential energy, both when it is compressed or stretched. Reason : In compressing or stretching, work is done on the spring against the restoring force.
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

9993.	Assertion : When height of a tube is less than liquid rise in the capillary tube, the liquid does not overflow. Reason : Product of radius of meniscus and height of liquid in capillary tube always 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» B. If both assertion and reason are true but reason is not the correct explanation of the assertion.

Discussion

9994.	Assertion : Ultraviolet radiation are of higher frequency waves are dangerous to human being. Reason : Ultraviolet radiation are absorbed by the atmosphere [AIIMS 1995]
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

9995.	If m is mass of electron, v its velocity, r the radius of stationary circular orbit around a nucleus with charge Ze, then from Bohr's first postulate, the kinetic energy \[K=\frac{1}{2}m{{v}^{2}}\]of the electron in C.G.S. system is equal to [NCERT 1977]
A.	\[\frac{1}{2}\frac{Z{{e}^{2}}}{r}\]
B.	\[\frac{1}{2}\frac{Z{{e}^{2}}}{{{r}^{2}}}\]
C.	\[\frac{Z{{e}^{2}}}{r}\]
D.	\[\frac{Ze}{{{r}^{2}}}\]
Answer» B. \[\frac{1}{2}\frac{Z{{e}^{2}}}{{{r}^{2}}}\]

Discussion

9996.	When two sound waves are superimposed, beats are produced when they have [MP PET 1995; CBSE PMT 1992, 99; DCE 2000; DPMT 2000, 01]
A.	Different amplitudes and phases
B.	Different velocities
C.	Different phases
D.	Different frequencies
Answer» E.

Discussion

9997.	A source of sound gives five beats per second when sounded with another source of frequency \[100\,{{s}^{-1}}\]. The second harmonic of the source together with a source of frequency \[205\,{{s}^{-1}}\] gives five beats per second. What is the frequency of the source [CBSE PMT 1995]
A.	\[105\,{{s}^{-1}}\]
B.	\[205\,{{s}^{-1}}\]
C.	\[95\,{{s}^{-1}}\]
D.	\[100\,{{s}^{-1}}\]
Answer» B. \[205\,{{s}^{-1}}\]

Discussion

9998.	An electron is moving in electric field and magnetic field it will gain energy from [DCE 1998]
A.	Electric field
B.	Magnetic field
C.	Both of these
D.	None of these
Answer» B. Magnetic field

Discussion

9999.	Two masses of 1kg and 16kg are moving with equal K.E. The ratio of magnitude of the linear momentum is [AIEEE 2002]
A.	1 : 2
B.	1 : 4
C.	\[1\,:\,\sqrt{2}\]
D.	\[\sqrt{2}\,:\,1\]
Answer» C. \[1\,:\,\sqrt{2}\]

Discussion

10000.	Assertion : The quantity L/R possesses dimensions of time. Reason : To reduce the rate of increases of current through a solenoid should increase the time constant (L/R). [AIIMS 2002]
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).

The unit of electric permittivity is [MP PET 2003]

Ultrasonic signal sent from SONAR returns to it after reflection from a rock after a lapse of 1 sec. If the velocity of ultrasound in water is 1600 ms?1, the depth of the rock in water is [JIPMER 2000]

An observer standing near the sea shore observes 54 waves per minute. If the wavelength of the water wave is 10m then the velocity of water wave is [Kerala (Engg.) 2005]

When air in a capacitor is replaced by a medium of dielectric constant K, the capacity [NCERT 1990; CPMT 1972, 82, 90; MP PMT 1993; MP PET 1994; KCET 1994]

In a circuit, the value of the alternating current is measured by hot wire ammeter as 10 ampere. Its peak value will be [MP PET 1996; AMU (Med.) 1999; KCET (Engg./Med.) 2000; CPMT 2003]

A metallic sheet is inserted between the plates of a parallel plate capacitor. The capacitance of the capacitor [Roorkee 2000]

Assertion : A beaker is completely filled with water at 4°C. It will overflow, both when heated or cooled. Reason : There is expansion of water below and above 4°C.

One mole of an ideal gas with \[\gamma =1.4\], is adiabatically compressed so that its temperature rises from 27°C to 35°C. The change in the internal energy of the gas is \[(R=8.3\,J/mol.K)\] [EAMCET 2001]

If the change in the value of ?g? at a height h above the surface of the earth is the same as at a depth x below it, then (both x and h being much smaller than the radius of the earth) [NCERT 1983; BHU 2002]

Equal charges \[q\] are placed at the four corners \[A,\,B,\,C,\,D\] of a square of length \[a\]. The magnitude of the force on the charge at B will be [MP PMT 1994; DPMT 2001]

An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The coulomb force \[\overrightarrow{F}\] between the two is (Where \[K=\frac{1}{4\pi {{\varepsilon }_{0}}}\]) [CBSE PMT 2003]

Assertion : The specific charge for positive rays is a characteristic constant. Reason : The specific charge depends on charge and mass of positive ions present in positive rays.

The specific charge of an electron is [MP PMT/PET 1998; J&K CET 2004; Pb. PET 2002; MH CET 1999]

Energy of the electron in nth orbit of hydrogen atom is given by \[{{E}_{n}}=-\frac{13.6}{{{n}^{2}}}eV\]. The amount of energy needed to transfer electron from first orbit to third orbit is [MH CET 2002; Kerala PMT 2002]

A bullet is fired from a rifle. If the rifle recoils freely, then the kinetic energy of the rifle is [AIIMS 1998; JIPMER 2001; UPSEAT 2000]

In a transformer, the number of turns in primary and secondary are 500 and 2000 respectively. If current in primary is 48 A, the current in the secondary is [Orissa PMT 2004]

Assertion : Heavy water is used as moderator in nuclear reactor. Reason : Water cool down the fast neutron.

Assertion : Reversible systems are difficult to find in real world. Reason : Most processes are dissipative in nature [AIIMS 2005]

Electric charges of \[1\mu C,\,-1\mu C\] and \[2\mu C\] are placed in air at the corners A, B and C respectively of an equilateral triangle ABC having length of each side 10 cm. The resultant force on the charge at C is [EAMCET (Engg.) 2000]

Hydrogen atom emits blue light when it changes from n = 4 energy level to the n = 2 level. Which colour of light would the atom emit when it changes from the n = 5 level to the n = 2 level [KCET 1993]

Which one of the series of hydrogen spectrum is in the visible region [RPMT 1999;MP PET 1990; MP PMT 1994; AFMC 1998; CBSE PMT 1990; MH CET 2004]

Assertion : When capacitive reactance is smaller than the inductive reactance in LCR current, e.m.f. leads the current . Reason : The phase angle is the angle between the alternating e.m.f. and alternating current of the circuit.

The attenuation in optical fibre is mainly due to [AFMC 2003]

Two waves \[y=0.25\sin 316\,t\] and \[y=0.25\sin 310\,t\] are travelling in same direction. The number of beats produced per second will be [CPMT 1993; JIPMER 2000]

The couple of tuning forks produces 2 beats in the time interval of 0.4 seconds. So the beat frequency is [CPMT 1996]

The wavelength of yellow line of sodium is 5896 Å. Its wave number will be [MP PET 2001]

As per Bohr model, the minimum energy (in eV) required to remove an electron from the ground state of doubly ionized Li atom (Z = 3) is [IIT 1997 Re-Exam; MH CET 2000]

A light bulb, a capacitor and a battery are connected together as shown here, with switch \[S\] initially open. When the switch \[S\]is closed, which one of the following is true [MP PMT 1995]

The colour of the second line of Balmer series is [J & K CET 2004]

Assertion : It is hotter over the top of a fire than at the same distance on the sides. Reason : Air surrounding the fire conducts more heat upwards. [AIIMS 2003]

The first member of the Paschen series in hydrogen spectrum is of wavelength 18,800 Å. The short wavelengths limit of Paschen series is [EAMCET (Med.) 2000]

\[+2C\] and \[+6C\] two charges are repelling each other with a force of \[12\,N\]. If each charge is given \[-2C\] of charge, then the value of the force will be [CPMT 1979; Kerala PMT 2002]

A 220 V, 50 Hz ac source is connected to an inductance of 0.2 H and a resistance of 20 ohm in series. What is the current in the circuit [MNR 1998; JIPMER 2001, 02]

In an ac circuit, a resistance of R ohm is connected in series with an inductance L. If phase angle between voltage and current be 45°, the value of inductive reactance will be [MP PMT/PET 1998]

L, C and R denote inductance, capacitance and resistance respectively. Pick out the combination which does not have the dimensions of frequency [MP PMT 1994]

The acceleration due to gravity at pole and equator can be related as [DPMT 2002]

Assertion : Lenz?s law violates the principle of conservation of energy. Reason : Induced e.m.f., opposes always the change in magnetic flux responsible for its production.

PQRS is a square loop made of uniform conducting wire the current enters the loop at P and leaves at S. Then the magnetic field will be [KCET 2000]

Assertion : If three capacitors of capacitance \[{{C}_{\text{1}}}

Assertion : A spring has potential energy, both when it is compressed or stretched. Reason : In compressing or stretching, work is done on the spring against the restoring force.

Assertion : When height of a tube is less than liquid rise in the capillary tube, the liquid does not overflow. Reason : Product of radius of meniscus and height of liquid in capillary tube always remains constant.

Assertion : Ultraviolet radiation are of higher frequency waves are dangerous to human being. Reason : Ultraviolet radiation are absorbed by the atmosphere [AIIMS 1995]

If m is mass of electron, v its velocity, r the radius of stationary circular orbit around a nucleus with charge Ze, then from Bohr's first postulate, the kinetic energy \[K=\frac{1}{2}m{{v}^{2}}\]of the electron in C.G.S. system is equal to [NCERT 1977]

When two sound waves are superimposed, beats are produced when they have [MP PET 1995; CBSE PMT 1992, 99; DCE 2000; DPMT 2000, 01]

A source of sound gives five beats per second when sounded with another source of frequency \[100\,{{s}^{-1}}\]. The second harmonic of the source together with a source of frequency \[205\,{{s}^{-1}}\] gives five beats per second. What is the frequency of the source [CBSE PMT 1995]

An electron is moving in electric field and magnetic field it will gain energy from [DCE 1998]

Two masses of 1kg and 16kg are moving with equal K.E. The ratio of magnitude of the linear momentum is [AIEEE 2002]

Assertion : The quantity L/R possesses dimensions of time. Reason : To reduce the rate of increases of current through a solenoid should increase the time constant (L/R). [AIIMS 2002]