41.

A charged particle enters in a strong perpendicular magnetic field. Then its kinetic energy

• increases

• decreases

• remains constant

• None of these

Calculate the current which will produce a deflection of 30° in a tangent galvanometer, if its reduction factor is 3 A.

• 1.732 A

• 0.732 A

• 3.732 A

• 2.732 A

Iron is ferromagnetic

• at all temperatures

• at NTP only

• above 770°C

• below 770°C

The inductance of a coil in which a current of 0.2 A is increasing at the rate of 0.5 A/s represents a power flow of 0.5 W, is

• 2 H

• 5 H

• 10 H

• 20 H

The mutual inductance of an induction coil is 5 H. In the primary coil, the current reduces from 5 A to zero is ${10}^{-3}$s What is the induced emf in the secondary coil?

• 2500 V

• 25000 V

• 2510 V

• Zero

Relative permeability of iron is 5500, then its magnetic susceptibility will be

• 5500 × 10⁷

• 5500 × 10^-7

• 5501

• 5499

What is shape of· magnet in moving coil galvanometer to make the radial magnetic field?

• Concave

• Horseshoe magnet

• Convex

• None of the above

A cyclotron can accelerate

• β-particles

• α-particles

• high-velocity gamma rays

• high-velocity X-rays

A potentiometer having the potential gradient of 2 mV/cm is used to measure the difference of potential across a resistance of 10Ω. If a length of 50 cm of the potentiometer wire is required to get the null points the current passing through the 10Ω resistor is (in mA)

• 1

• 2

• 5

• 10

Maximum energy is evolved during which of the following transitions?

• n = 1 to n= 2

• n = 2 to n= 6

• n = 2 to n= 1

• n = 6 to n= 2