Alternating Current — Physics STD 12 Science — Question

Vertical component of earth's magnetic field is zero:

The value of 1 amu is equal to:

The mutual inductance between a primary and secondary circuits is 0.5 H. The resistances of the primary and the secondary circuits are 20 ohms and 5 ohms respectively. To generate a current of 0.4 A in the secondary, current in the primary must be changed at the rate of

(a) 4.0 A/s

(b) 16.0 A/s

(c) 1.6 A/s

(d) 8.0 A/s

Radio wave diffract around building although light waves do not. The reason is that radio waves

(a) Travel with speed larger than c	(b) Have much larger wavelength than light
(c) Carry news	(d) Are not electromagnetic waves

Which of the following is the best definition of the uncertainty principle?

An inductor coil of some resistance is connected to an AC source. Which of the following quantities have zero average value over a cycle?

1. Current.
2. Induced emf in the inductor.
3. Joule heat.
4. Magnetic energy stored in the inductor.

Two concentric circular coils of ten turns each are situated in the same plane. Their radii are 20 and 40 cm and they carry respectively 0.2 and 0.3 ampere current in opposite direction. The magnetic field in   at the centre is

(a)

(b)

(c)

(d)

Atomic mass of an element is:

Gravitational force has only on sign but coulomb force has:

Choose the correct option about light.