Electric Charges and Fields — Physics STD 12 Science — Question

In the given circuit, with steady current, the potential drop across the capacitor must be

(a) V

(b) V / 2

(c) V / 3

(d) 2V / 3

The length of the compound microscope is 14 cm. The magnifying power for relaxed eye is 25. If the focal length of eye lens is 5 cm, then the object distance for objective lens will be

(a) 1.8 cm

(b)  1.5 cm

(c) 2.1 cm

(d)  2.4 cm

Cathode rays are

(a) Positive rays

(b) Neutral rays

(c) He rays

(d) Electron waves

Let F_pp' F_pn and F_nn fill denote the magnitudes of the nuclear force by a proton on a proton, by a proton on a neutron and by a neutron on a neutron respectively. When the separation is 1fm:

The minimum intensity of light to be detected by human eye is  . The number of photons of wavelength  5.6   entering the eye, with pupil area  , per second for vision will be nearly

(a) 100

(b) 200

(c) 300

(d) 400

A moving coil galvanometer has N number of turns in a coil of effective area A, it carries a current I. The magnetic field B is radial. The torque acting on the coil is

(a)

(b)

(c)

(d) NABI

In a fission process, nucleus A divides into two nuclei B and C, their binding energies being  and   respectively. Then

(a)

(b)

(c)

(d)

A capacitor acts as an infinite resistance for:

A wire loop is rotated in a uniform magnetic field about an axis perpendicular to the field. The direction of the current induced in the loop reverse once each.

Two cars of unequal masses use similar tyres. If they are moving at the same initial speed, the minimum stopping distance:

1. Is smaller for the heavier car.
2. Is smaller for the lighter car.
3. Is same for both cars.
4. Depends on the volume of the car.