Ques. A 1 em segment of a wire lying along x-axis carries current of 0.5 A along +x direction. A magnetic field vec B =(0.4 mT) hat j + (0.6 m T) k is switched on in the region. The force acting on the segment is :

Correct Answer : Option (B)

Ques.The ratio of the number of turns of the primary to the secondary coils in an ideal transformer is 20: 1. If 240 V ac is applied from a source to the primary coil of transformer and a 6.0 Q resistor is connected across the output terminals, then current drawn by the transformer from the source will be-
(A) 4.0 A
(C) 0.97 A
(B) 3.8 A
(D) 0.10 A

Correct Answer : Option (D) 0.10 A

Ques. Assertion (A): The potential energy of an electron revolving in any stationary orbit in a hydrogen atom is positive.
Reason (R) : The total energy of a charged particle is always positive.

(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false and Reason (R) is also false.

Correct Answer : Option (D) Assertion (A) is false and Reason (R) is also false.

Ques. You are required to design an air-filled solenoid of inductance 0.016 Η having a length 0.81 m and radius 0.02 m. The number of turns in the solenoid should be
(A) 2592
(C) 2976
(B) 2866
(D) 3140

Correct Answer : Option (B) 2866