The direction of propagation of electromagnetic wave is along

• Electric field vector, E

• Magnetic field vector, B

• E . B

• E × B

Assume that a radio station is about 200 km away at your location and the station operates 972 kHz. How long does it take for an electromagnetic signal to travel from the station to you and how many wave crests does it send out per second ?

• 666 µs and 9.72 × 10⁵ crests per second

• 666 µs and 972 × 10⁵ crests per second

• 555 µs and 97.2 × 10⁷ crests per second

• 555 µs and 0.972 × 10⁵ crests per second

The electric field portion of an electromagnetic wave is given by (all variables in SI units) E = 10^-4 sin(6 x 10⁵ t − 0.01 x). The frequency (f) and the speed (v) of electromagnetic wave are

• f = 30/π kHz and v = 1.5 × 10⁷ m/s

• f = 90/π kHz and v = 6.0 × 10⁷ m/s

• f = 300/π kHz and v = 6.0 × 10⁷ m/s

• f = 600/π kHz and v = 7.5 × 10⁷ m/s

If copper and silicon pieces are heated, the resistance of

• each will increase

• each will decrease

• copper will increase and silicon will decrease

• copper will decrease and silicon will increase

If a magnet is dropped through a vertical hollow copper tube, then

• the time taken to reach the ground is longer than the time taken, if the tube was made out of plastic

• the magnet will get attracted and stick to the copper tube

• the time taken to reach the ground is longer than the time taken, if the tube was made out of stainless steel

• the time taken to reach the ground does not depend on the radius of the copper tube

Consider a circular wire loop of radius R spinning about a diametrical chord which is perpendicular to uniform magnetic field $\left({\mathrm{B}}_0\hat{\mathrm{k}}\right)$

• The magnitude of the induced EMF in the loop is maximum when the plane of the loop is perpendicular to B

• Flux through the loop is maximum when the plane of the loop is perpendicular to B

• The direction of induced current remains same during the spinning motion of the loop

• EMF induced will be the same for a larger radius of the loop in the same field

An electric motor which loaded has an effective resistance of 30 Ω and an inductive reactance of 40 Ω.If the motor is powered by a source with maximum voltage of 420 V, the maximum current is

• 6 A

• 8.4 A

• 10 A

• 12 A

58.

If the rms value of sinusoidal input to a full wave rectifier is ${\mathrm{V}}_0/\sqrt{2}$, then the rms value of the rectifier's output is

• ${\mathrm{V}}_0/\sqrt{2}$

• ${{\mathrm{V}}_0}^2/\sqrt{2}$

• V₀²/2

• $\sqrt{2} {{\mathrm{V}}_0}^2$

The speed of light in vacuum is equal to

• µ₀ε₀

• µ₀²ε₀²

• $\frac{1}{\sqrt{{\mathrm{\mu }}_0{\mathrm{\epsilon }}_0}}$

• $\sqrt{{\mathrm{\mu }}_0{\mathrm{\epsilon }}_0}$

In Young's double slits experiment, if the separation between the slits is halved, and the distance between the slits and the screen is doubled, then the fringe width compared to the original one will be

• Unchanged

• Halved

• Doubled

• Quadrupled