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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 7401. |
The drift velocity does not depend upon [BHU 2001] |
| A. | Cross-section of the wire |
| B. | Length of the wire |
| C. | Number of free electrons |
| D. | Magnitude of the current |
| Answer» C. Number of free electrons | |
| 7402. |
If a wire of resistance R is melted and recasted to half of its length, then the new resistance of the wire will be [KCET (Med.) 2001] |
| A. | R/4 |
| B. | R/2 |
| C. | R |
| D. | 2R |
| Answer» B. R/2 | |
| 7403. |
Calculate the amount of charge flowing in 2 minutes in a wire of resistance 10 W when a potential difference of 20 V is applied between its ends [Kerala (Engg.) 2001] |
| A. | 120 C |
| B. | 240 C |
| C. | 20 C |
| D. | 4 C |
| Answer» C. 20 C | |
| 7404. |
If an observer is moving with respect to a stationary electron, then he observes [DCE 2001] |
| A. | Only magnetic field |
| B. | Only electric field |
| C. | Both A and B |
| D. | None of the above |
| Answer» D. None of the above | |
| 7405. |
A nichrome wire 50 cm long and one square millimetre cross-section carries a current of 4A when connected to a 2V battery. The resistivity of nichrome wire in ohm metre is [EAMCET 2001] |
| A. | 1 × \[{{10}^{-6}}\] |
| B. | 4 × \[{{10}^{-7}}\] |
| C. | 3 × \[{{10}^{-7}}\] |
| D. | 2 × \[{{10}^{-7}}\] |
| Answer» B. 4 × \[{{10}^{-7}}\] | |
| 7406. |
If potential \[V=100\pm 0.5\,Volt\] and current \[I=10\pm 0.2\] amp are given to us. Then what will be the value of resistance [RPET 2001] |
| A. | \[10\pm 0.7\,ohm\] |
| B. | \[5\pm 2\,ohm\] |
| C. | \[0.1\pm 0.2ohm\] |
| D. | None of these |
| Answer» E. | |
| 7407. |
The temperature coefficient of resistance for a wire is \[0.00125/{}^\circ C\]. At 300K its resistance is 1 ohm. The temperature at which the resistance becomes 2 ohm is [IIT 1980; MP PET 2002; KCET 2003; MP PMT 2001; Orissa JEE 2002] |
| A. | 1154 K |
| B. | 1100 K |
| C. | 1400 K |
| D. | 1127 K |
| Answer» E. | |
| 7408. |
The charge of an electron is 1.6 × 10?19 C. How many electrons strike the screen of a cathode ray tube each second when the beam current is 16 mA [AMU (Med.) 2000] |
| A. | \[{{10}^{17}}\] |
| B. | \[{{10}^{19}}\] |
| C. | \[{{10}^{19}}\] |
| D. | \[{{10}^{17}}\] |
| Answer» B. \[{{10}^{19}}\] | |
| 7409. |
An electron revolves \[6\text{ }\times \text{ }{{10}^{15}}times/sec\]in circular loop. The current in the loop is [MNR 1995; UPSEAT 2000] |
| A. | 0.96 mA |
| B. | 0.96 m A |
| C. | 28.8 A |
| D. | None of these |
| Answer» B. 0.96 m A | |
| 7410. |
A rod of a certain metal is 1.0 m long and 0.6 cm in diameter. Its resistance is 3.0 × \[{{10}^{-3}}\] ohm. Another disc made of the same metal is 2.0 cm in diameter and 1.0 mm thick. What is the resistance between the round faces of the disc [MP PET 2000] |
| A. | \[\text{1}.\text{35 }\times ~{{10}^{-8}}hm\] |
| B. | 2.70 × \[{{10}^{-7}}\] ohm |
| C. | 4.05 × \[{{10}^{-6}}\] ohm |
| D. | 8.10 × \[{{10}^{-5}}\] ohm |
| Answer» C. 4.05 × \[{{10}^{-6}}\] ohm | |
| 7411. |
Equal potentials are applied on an iron and copper wire of same length. In order to have the same current flow in the two wires, the ratio r (iron)/r (copper) of their radii must be (Given that specific resistance of iron = \[1.0\times {{10}^{-7}}\]ohm?m and specific resistance of copper = \[1.7\times {{10}^{-8}}\]ohm-m) [MP PMT 2000] |
| A. | About 1.2 |
| B. | About 2.4 |
| C. | About 3.6 |
| D. | About 4.8 |
| Answer» C. About 3.6 | |
| 7412. |
If an electron revolves in the path of a circle of radius of \[0.5\text{ }\times \text{ }{{10}^{10}}m\]at frequency of \[5\text{ }\times \text{ }{{10}^{15}}cycles/s\]the electric current in the circle is (Charge of an electron \[=\text{ }1.6\text{ }\times \text{ }{{10}^{19}}C\]) [EAMCET 2000] |
| A. | 0.4 mA |
| B. | 0.8 mA |
| C. | 1.2 mA |
| D. | 1.6 mA |
| Answer» C. 1.2 mA | |
| 7413. |
The resistance of a conductor is 5 ohm at 50oC and 6 ohm at 100oC. Its resistance at 0oC is [KCET 2000] |
| A. | 1 ohm |
| B. | 2 ohm |
| C. | 3 ohm |
| D. | 4 ohm |
| Answer» E. | |
| 7414. |
A uniform wire of resistance R is uniformly compressed along its length, until its radius becomes n times the original radius. Now resistance of the wire becomes [KCET 2000] |
| A. | \[\frac{R}{{{n}^{4}}}\] |
| B. | \[\frac{R}{{{n}^{2}}}\] |
| C. | \[\frac{R}{n}\] |
| D. | nR |
| Answer» B. \[\frac{R}{{{n}^{2}}}\] | |
| 7415. |
Conductivity increases in the order of [AFMC 2000] |
| A. | Al, Ag, Cu |
| B. | Al, Cu, Ag |
| C. | Cu, Al, Ag |
| D. | Ag, Cu, Al |
| Answer» C. Cu, Al, Ag | |
| 7416. |
The resistivity of iron is\[1\times {{10}^{-7}}\,ohm-m\]. The resistance of a iron wire of particular length and thickness is 1 ohm. If the length and the diameter of wire both are doubled, then the resistivity in \[ohm-m\] will be [CPMT 1983; DPMT 1999] |
| A. | \[1\times {{10}^{-7}}\] |
| B. | \[2\times {{10}^{-7}}\] |
| C. | \[4\times {{10}^{-7}}\] |
| D. | \[8\times {{10}^{-7}}\] |
| Answer» B. \[2\times {{10}^{-7}}\] | |
| 7417. |
The resistance of a coil is 4.2 W at 100o C and the temperature coefficient of resistance of its material is 0.004/o C. Its resistance at 0o C is [KCET 1999] |
| A. | 6.5 W |
| B. | 5 W |
| C. | 3 W |
| D. | 4 W |
| Answer» D. 4 W | |
| 7418. |
Masses of three wires of copper are in the ratio of 1 : 3 : 5 and their lengths are in the ratio of \[5:3:1.\] The ratio of their electrical resistances are [AFMC 2000] |
| A. | 1 : 3 : 5 |
| B. | 5 : 3 : 1 |
| C. | 1 : 15 : 125 |
| D. | 125 : 15 : 1 |
| Answer» E. | |
| 7419. |
If an electric current is passed through a nerve of a man, then man [UPSEAT 1999] |
| A. | Begins to laugh |
| B. | Begins to weep |
| C. | Is excited |
| D. | Becomes insensitive to pain |
| Answer» D. Becomes insensitive to pain | |
| 7420. |
A current I is passing through a wire having two sections P and Q of uniform diameters d and d/2 respectively. If the mean drift velocity of electrons in sections P and Q is denoted by vP and vQ respectively, then [Roorkee 1999] |
| A. | \[{{v}_{\text{P}}}={{v}_{\text{Q}}}\] |
| B. | \[{{v}_{\text{P}}}={{v}_{\text{Q}}}\] |
| C. | \[{{v}_{\text{P}}}=\frac{1}{4}{{v}_{\text{Q}}}\] |
| D. | \[{{v}_{\text{P}}}=\text{ 2}{{v}_{\text{Q}}}\] |
| Answer» D. \[{{v}_{\text{P}}}=\text{ 2}{{v}_{\text{Q}}}\] | |
| 7421. |
1.6 mA current is flowing in conducting wire then the number of electrons flowing per second is [RPMT 1999] |
| A. | \[\text{1}{{0}^{\text{11}}}\] |
| B. | \[\text{1}{{0}^{\text{16}}}\] |
| C. | \[\text{1}{{0}^{\text{19}}}\] |
| D. | \[\text{1}{{0}^{\text{15}}}\] |
| Answer» C. \[\text{1}{{0}^{\text{19}}}\] | |
| 7422. |
\[{{\sigma }_{1}}\] and \[{{\sigma }_{2}}\] are the electrical conductivities of Ge and Na respectively. If these substances are heated, then |
| A. | Both \[{{\sigma }_{1}}\] and \[{{\sigma }_{2}}\] increase |
| B. | \[{{\sigma }_{1}}\] increases and \[{{\sigma }_{2}}\] decreases |
| C. | \[{{\sigma }_{1}}\] decreases and \[{{\sigma }_{2}}\] increases |
| D. | Both \[{{\sigma }_{1}}\] and \[{{\sigma }_{2}}\] decrease |
| Answer» C. \[{{\sigma }_{1}}\] decreases and \[{{\sigma }_{2}}\] increases | |
| 7423. |
\[20\,\mu A\] current flows for 30 seconds in a wire, transfer of charge will be [RPMT 1997] |
| A. | \[2\times {{10}^{-4}}C\] |
| B. | \[4\times {{10}^{-4}}C\] |
| C. | \[6\times {{10}^{-4}}C\] |
| D. | \[8\times {{10}^{-4}}C\] |
| Answer» D. \[8\times {{10}^{-4}}C\] | |
| 7424. |
Two rods of same material and length have their electric resistance in ratio \[1:2\]. When both rods are dipped in water, the correct statement will be [RPMT 1997] |
| A. | A has more loss of weight |
| B. | B has more loss of weight |
| C. | Both have same loss of weight |
| D. | Loss of weight will be in the ratio \[1:2\] |
| Answer» B. B has more loss of weight | |
| 7425. |
Two wires A and B of same material and same mass have radius 2rand r. If resistance of wire A is \[34\,\Omega \], then resistance of B will be [RPET 1997] |
| A. | \[544\,\Omega \] |
| B. | \[272\,\Omega \] |
| C. | \[68\,\Omega \] |
| D. | \[17\,\Omega \] |
| Answer» B. \[272\,\Omega \] | |
| 7426. |
The resistivity of alloys \[={{R}_{\text{alloy}}}\]; the resistivity of constituent metals \[{{R}_{\text{metal}}}\]. Then, usually [KCET 1994] |
| A. | \[{{R}_{\text{alloy}}}={{R}_{\text{metal}}}\] |
| B. | \[{{R}_{\text{alloy}}}<{{R}_{\text{metal}}}\] |
| C. | There is no simple relation between \[{{R}_{\text{alloy}}}\] and \[{{R}_{\text{metal}}}\] |
| D. | \[{{R}_{\text{alloy}}}>{{R}_{\text{metal}}}\] |
| Answer» E. | |
| 7427. |
In a neon discharge tube \[2.9\times {{10}^{18}}\,N{{e}^{+}}\] ions move to the right each second while \[1.2\times {{10}^{18}}\] electrons move to the left per second. Electron charge is \[1.6\times {{10}^{-19}}C\]. The current in the discharge tube [MP PET 1999] |
| A. | 1 A towards right |
| B. | 0.66 A towards right |
| C. | 0.66 A towards left |
| D. | Zero |
| Answer» C. 0.66 A towards left | |
| 7428. |
A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/ quantities constant along the length of the conductor is/are [KCET 1994, IIT 1997 Cancelled; CBSE PMT 2001] |
| A. | Current, electric field and drift speed |
| B. | Drift speed only |
| C. | Current and drift speed |
| D. | Current only |
| Answer» E. | |
| 7429. |
The conductivity of a superconductor is [Similar to KCET 1993; MP PMT/PET 1998] |
| A. | Infinite |
| B. | Very large |
| C. | Very small |
| D. | Zero |
| Answer» B. Very large | |
| 7430. |
The resistivity of a wire depends on its [MP PMT/PET 1998] |
| A. | Length |
| B. | Area of cross-section |
| C. | Shape |
| D. | Material |
| Answer» E. | |
| 7431. |
In a wire of circular cross-section with radius r, free electrons travel with a drift velocity V when a current I flows through the wire. What is the current in another wire of half the radius and of the same material when the drift velocity is 2V [MP PET 1997] |
| A. | 2I |
| B. | I |
| C. | \[I/2\] |
| D. | \[I/4\] |
| Answer» D. \[I/4\] | |
| 7432. |
We are able to obtain fairly large currents in a conductor because [Haryana CEE 1996] |
| A. | The electron drift speed is usually very large |
| B. | The number density of free electrons is very high and this can compensate for the low values of the electron drift speed and the very small magnitude of the electron charge |
| C. | The number density of free electrons as well as the electron drift speeds are very large and these compensate for the very small magnitude of the electron charge |
| D. | The very small magnitude of the electron charge has to be divided by the still smaller product of the number density and drift speed to get the electric current |
| Answer» C. The number density of free electrons as well as the electron drift speeds are very large and these compensate for the very small magnitude of the electron charge | |
| 7433. |
The resistance of a discharge tube is [AFMC 1996; CBSE PMT 1999] |
| A. | Ohmic |
| B. | Non-ohmic |
| C. | Both A and B |
| D. | Zero |
| Answer» C. Both A and B | |
| 7434. |
If the resistance of a conductor is 5 W at 50oC and 7 W at 100oC then the mean temperature coefficient of resistance of the material is [Pb PET 2000] |
| A. | \[0.008{{/}^{o}}C\] |
| B. | \[0.006{{/}^{o}}C\] |
| C. | \[0.004{{/}^{o}}C\] |
| D. | \[0.001{{/}^{o}}C\] |
| Answer» B. \[0.006{{/}^{o}}C\] | |
| 7435. |
A potential difference of V is applied at the ends of a copper wire of length l and diameter d. On doubling only d, drift velocity [MP PET 1995] |
| A. | Becomes two times |
| B. | Becomes half |
| C. | Does not change |
| D. | Becomes one fourth |
| Answer» D. Becomes one fourth | |
| 7436. |
If a 0.1 % increase in length due to stretching, the percentage increase in its resistance will be [MNR 1990; MP PMT 1996; UPSEAT 1999; MP PMT 2000] |
| A. | 0.2 % |
| B. | 2 % |
| C. | 1 % |
| D. | 0.1 % |
| Answer» B. 2 % | |
| 7437. |
All of the following statements are true except [Manipal MEE 1995] |
| A. | Conductance is the reciprocal of resistance and is measured in Siemens |
| B. | Ohm's law is not applicable at very low and very high temperatures |
| C. | Ohm's law is applicable to semiconductors |
| D. | Ohm's law is not applicable to electron tubes, discharge tubes and electrolytes |
| Answer» D. Ohm's law is not applicable to electron tubes, discharge tubes and electrolytes | |
| 7438. |
A solenoid is at potential difference 60 V and current flows through it is 15 ampere, then the resistance of coil will be [AFMC 1995] |
| A. | \[4\,\Omega \] |
| B. | \[8\,\Omega \] |
| C. | \[0.25\,\Omega \] |
| D. | \[2\,\Omega \] |
| Answer» B. \[8\,\Omega \] | |
| 7439. |
The reciprocal of resistance is [AFMC 1995] |
| A. | Conductance |
| B. | Resistivity |
| C. | Voltage |
| D. | None of the above |
| Answer» B. Resistivity | |
| 7440. |
Which of the following has a negative temperature coefficient [AFMC 1995] |
| A. | C |
| B. | Fe |
| C. | Mn |
| D. | Ag |
| Answer» B. Fe | |
| 7441. |
The resistance of a wire is R. If the length of the wire is doubled by stretching, then the new resistance will be [Roorkee 1992; AFMC 1995; KCET 1993; AMU (Med.) 1999; CBSE PMT 1999; MP PET 2001; UPSEAT 2001] |
| A. | 2R |
| B. | 4R |
| C. | R |
| D. | \[\frac{R}{4}\] |
| Answer» C. R | |
| 7442. |
For a metallic wire, the ratio \[V/i\] \[(V=\] the applied potential difference, i = current flowing) is [MP PMT 1994; BVP 2003] |
| A. | Independent of temperature |
| B. | Increases as the temperature rises |
| C. | Decreases as the temperature rises |
| D. | Increases or decreases as temperature rises, depending upon the metal |
| Answer» C. Decreases as the temperature rises | |
| 7443. |
A copper wire of length 1 m and radius 1 mm is joined in series with an iron wire of length 2 m and radius 3 mm and a current is passed through the wires. The ratio of the current density in the copper and iron wires is [MP PMT 1994] |
| A. | 18 : 1 |
| B. | 9 : 1 |
| C. | 6 : 1 |
| D. | 2 : 3 |
| Answer» C. 6 : 1 | |
| 7444. |
A metal wire of specific resistance \[64\times {{10}^{-6}}ohm-cm\] and length 198 cm has a resistance of 7 ohm, the radius of the wire will be [MP PET 1994] |
| A. | 2.4 cm |
| B. | 0.24 cm |
| C. | 0.024 cm |
| D. | 24 cm |
| Answer» D. 24 cm | |
| 7445. |
Resistance of tungsten wire at \[150{}^\circ C\] is \[133\,\Omega \]. Its resistance temperature coefficient is \[0.0045/{}^\circ C\]. The resistance of this wire at \[500{}^\circ C\] will be [DPMT 2004] |
| A. | \[180\,\Omega \] |
| B. | \[225\,\Omega \] |
| C. | \[258\,\Omega \] |
| D. | \[317\,\Omega \] |
| Answer» D. \[317\,\Omega \] | |
| 7446. |
The resistance of a wire is\[10\,\Omega \]. Its length is increased by 10% by stretching. The new resistance will now be [CPMT 2000; Pb PET 2004] |
| A. | \[12\,\Omega \] |
| B. | \[1.2\,\Omega \] |
| C. | \[13\,\Omega \] |
| D. | \[11\,\Omega \] |
| Answer» B. \[1.2\,\Omega \] | |
| 7447. |
Which one is not the correct statement [NCERT 1978] |
| A. | \[1\,volt\times 1\,coulomb=1\,joule\] |
| B. | \[1\,volt\times 1\,ampere=1\,joule/second\] |
| C. | \[1\,volt\times 1\,watt=1\,H.P.\] |
| D. | Watt-hour can be expressed in eV |
| Answer» D. Watt-hour can be expressed in eV | |
| 7448. |
The relaxation time in conductors [DPMT 2003] |
| A. | Increases with the increase of temperature |
| B. | Decreases with the increase of temperature |
| C. | It does not depend on temperature |
| D. | All of sudden changes at 400 K |
| Answer» C. It does not depend on temperature | |
| 7449. |
If \[n,\,e,\,\tau \] and m respectively represent the density, charge relaxation time and mass of the electron, then the resistance of a wire of length \[l\] and area of cross-section \[A\] will be [CPMT 1992] |
| A. | \[\frac{ml}{n{{e}^{2}}\tau A}\] |
| B. | \[\frac{m{{\tau }^{2}}A}{n{{e}^{2}}l}\] |
| C. | \[\frac{n{{e}^{2}}\tau A}{2ml}\] |
| D. | \[\frac{n{{e}^{2}}A}{2m\tau l}\] |
| Answer» B. \[\frac{m{{\tau }^{2}}A}{n{{e}^{2}}l}\] | |
| 7450. |
For which of the following the resistance decreases on increasing the temperature [MP PET 1993] |
| A. | Copper |
| B. | Tungsten |
| C. | Germanium |
| D. | Aluminium |
| Answer» D. Aluminium | |