Nuclei — Physics STD 12 Science — Question

Assertion : The television broadcasting becomes weaker with increasing distance.

Reason    :  The power transmitted from TV transmitter varies inversely as the distance of the receiver

(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.

Two bulbs each marked 100 W, 220 V are connected in series across 220 V supply. The power consumed by them, when lit, is

An electric bulb illuminates a plane surface. The intensity of illumination on the surface at a point 2m away from the bulb is 5  phot (lumen/cm²). The line joining the bulb to the point makes an angle of 60^o with the normal to the surface. The intensity of the bulb in candela is

(a) 40

(b) 40

(c) 20

(d) 40

A moving charge will gain energy due to the application of

(a) Electric field

(b) Magnetic field

(c) Both of these

(d) None of these

What happens when a glass rod is rubbed with silk?

Current in the circuit is wattless, if.

A thin, metallic spherical shell contains a charge Q on it. A point charge q is placed at the centre of the shell and another charge q₁ is placed outside it as shown in figure. All the three charges are positive. The force on the charge at the centre is:

1. Towards left.
2. Towards right.
3. Upward.
4. Zero.

A substance is behaving as convex lens in air and concave in water, then its refractive index is

(a) Smaller than air	(b) Greater than both air and water
(c) Greater than air but less than water	(d) Almost equal to water