Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

In an X-ray tube electrons bombarding the target produce X-rays of minimum wavelength 1 Å. What must be the energy of bombarding electrons

(a) 13375 eV

(b) 12375 eV

(c) 14375 eV

(d) 15375 eV

An electric bulb is rated 220 volt and 100 watt. Power consumed by it when operated on 110 volt is

(a) 50 watt

(b) 75 watt

(c) 90 watt

(d) 25 watt

The work function of aluminium is 4.2 eV. If two photons, each of energy 3.5 eV strike an electron of aluminium, then emission of electrons will be

(a) Possible

(b) Not possible

(c) Data is incomplete

(d) Depend upon the density of the surface

We combined a convex lens of focal length f₁ and concave lens of focal lengths f₂ and their combined focal length was F.  The combination of these lenses will behave like a concave lens, if

(a) f1 > f2

(b) f1 < f2

(c) f1 = f2

(d) f1 ≤ f2

Consider the following two statements regarding a linearly polarised, plane electromagnetic wave:

1. The electric field and the magnetic field have equal average values.
2. The electric energy and the magnetic energy have equal average values.

1. Both A and B are true.
2. A is false but B is true.
3. B is false but A is true
4. Both A and B are false.

When the light source is moving away, the Doppler effect for light is known as:

Two point white dots are 1mm apart on a black paper. They are viewed by eye of pupil of diameter 3mm. Approximately what is the maximum distance up to which these dots can be resolved by the eye.

Fusion reactions take place at high temperature because:

A magnet of magnetic moment 2  is aligned in the direction of magnetic field of 0.1 T. What is the net work done to bring the magnet normal to the magnetic field

(a) 0.1  J

(b) 0.2 J

(c) 1 J

(d) 2 J