Alternating Current — Physics STD 12 Science — Question

Which of the following is a natural magnet?

For the production of characteristic   X-ray, the electron transition is

(a) n = 2 to n = 1

(b) n = 3 to  n = 2

(c) n = 3 to n = 1

(d) n = 4 to n = 1

Vapour is injected at a uniform rate in a closed veseel which was initially evacuated. The pressure in the vessel:

1. Increaaes continuously.
2. Decreases continuously.
3. First increases and then decreases.
4. First increases and then becomes constant.

The ionisation energy of hydrogen atom is 13.6 eV. Following Bohr's theory, the energy corresponding to a transition between the 3rd and the 4th orbit is

(a) 3.40 eV

(b) 1.51 eV

(c) 0.85 eV

(d) 0.66 eV

Electric lines of force about negative point charge are

(a) Circular, anticlockwise	(b) Circular, clockwise
(c) Radial, inward	(d) Radial, outward

If the distance between the plates of parallel plate capacitor is halved and the dielectric constant of dielectric is doubled, then its capacity will

(a) Increase by 16 times	(b) Increase by 4 times
(c) Increase by 2 times	(d) Remain the same

The dependence of the short wavelength limit   on the accelerating potential V is represented by the curve of figure

(a) A

(b) B

(c) C

(d) None of these

In the following circuit, bulb rated as 1.5 V, 0.45 W. If bulbs glows with full intensity then what will be the equivalent resistance between X and Y

(a) 0.45 W

(b) 1 W

(c) 3 W

(d) 5 W