Electromagnetic Waves — Physics STD 12 Science — Question

The minimum frequency v of continuous X-rays is related to the applied potential difference V as

(a) v ∝

(b) v ∝ v

(c) v ∝

(d) v ∝

If in a parallel plate capacitor, which is connected to a battery, we fill dielectrics in whole space of its plates, then which of the following increases?

As compared to ¹²C atom, ¹⁴C atom has:

1. Two extra protons and two extra electrons.
2. Two extra protons but no extra electron.
3. Two extra neutrons and no extra electron.
4. Two extra neutrons and two extra electrons.

In the absence of an electric field, the mean velocity of free electrons in a conductor at absolute temperature (T) is:

Which of the following is an example of a molecule whose centre of mass of positive and negative charges does not coincide each other?

Inductance plays the role of

A bulb rated at (100W – 200V) is used on a 100V line. The current in the bulb is

(a) amp

(b) 4 amp

(c)  amp

(d) 2 amp

When we rub our comb with hair and then take near to the paper pieces, all pieces get stuck to the comb. This happens due tyo which phenomena?

Assertion  :   When a magnetic dipole is placed in a non uniform magnetic field, only a torque acts on the dipole.

Reason      : Force would also acts on dipole if magnetic field were uniform.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

A spring-mass system occillates in a car. if the car accelerates on a horizontal road, the frequency of oscillation will:

1. Increase.
2. Decrease.
3. Remain same.
4. Become zero.