moving charges questions neet questions.pptx

it gives important question of moving charges

1. . Two thin long parallel wires separated by a distance b are carrying a current i amp each. The magnitude of the force per unit length exerted by one wire on the other is a) μ /(i 2 / b 2 ) b) μ i 2 / 2 π b c) π i/2 π b d) μ i/4πb

2. The magnetic field at centre of a hexagonal coil of side l carrying a current is a) b) c) d) Zero

3. The magnetic field at centre of a hexagonal coil of side l carrying a current is

4. The magnetic field strength at a point P distant r due to an infinite straight wire as shown in the figure carrying a current is

5. . A wire bent in the form of a sector of radius r subtending an angle θ at centre , as shown in figure is carrying a current i . The magnetic field at O is

6. . If the resistance of the upper half of a rigid loop is twice of that of the lower half, the magnitude of magnetic induction at the centre is equal to

7. A beam of ions with velocity 2 x 10 5 m/s enter normally into a uniform magnetic field of 4 x 10 -2 T. If the specific charge of the ions is 5 x 10 7 C/kg, the radius of the circular path described will be

8. Current sensitivity of a moving coil galvanometer is 5 div / mA and its voltage sensitivity (angular deflection per unit voltage applied) is 20 div/V. The resistance of the galvanometer is a) 40 Ω b) 25 Ω c) 250 Ω d) 500 Ω

9. Two toroids 1 and 2 have total number of turns 200 and 100 respectively with average radii 40 cm and 20 cm respectively. If they carry same current I, the ratio of the magnetic fields along the two loops is a) 1:1 b) 4:1 c) 2:1 d) 1:2

10. Ionized hydrogen atoms and α – particle with same momenta enters perpendicular to a constant magnetic field, B. The ratio of their radii of their paths r H : r α a) 1:4 b) 2:1 c) 1:2 d) 4:1

11. A long solenoid of 50 cm length having 100 turns carries a current of 2.5A. The magnetic field at the centre of the solenoid is [ μ = 4 π x 10 -7 T mA -1 ] a) 3.14 x 10 -4 T b) 6.28 x 10 -5 T c) 3.14 x 10 -5 T d) 6.28 x 10 -4 T

12. Two particles x and y having equal charges after being accelerated through the same potential difference enter a region of uniform magnetic field and describe circular paths of radii R 1 and R 2 respectively. The ratio of the mass of x and y is a) (R 1 / R 2 ) 1/2 b) (R 2 / R 1 ) c) (R 1 / R 2 ) 2 d) (R 1 / R 2 )

13. The current in straight wire if the magnetic field 10 –6 Wm –2 produced at 0.02 m away from it is a) 0.1 A b) 1 A c) Zero d) 10 A

14. A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil for same current will be a) nB b) n 2 B c) 2nB d) 2n 2 B

15. A charge +Q is moving upwards vertically. It enters a magnetic field directed to north. The force on the charge will be towards a) North b) South c) East d) West

16. An electron projected in a perpendicular uniform magnetic field of 3 x 10 -3 T, moves in a circle of radius 4 mm. The linear momentum of electron (in kg- ms ) is a) 192 × 10 –21 b) 1.2 × 10 –24 c) 1.92 × 10 –24 d) 1.2 × 10 –21

17. The ratio of magnetic field and magnetic moment at the centre of a current carrying circular loop is x. When both the current and radius is doubled the ratio will be a) x/8 b) x/4 c) x/2 d) 2x