Model Paper 3 — Physics STD 12 Science — Question

If intensity of incident light is increased in PEE then which of the following is true

(a) Maximum K.E. of ejected electron will increase

(b) Work function will remain unchanged

(c) Stopping potential will decrease

(d) Maximum K.E. of ejected electron will decrease

A coil is wound as a transformer of rectangular cross-section. If all the linear dimensions of the transformer are increased by a factor 2 and the number of turns per unit length of the coil remain the same, the self  inductance increased by a factor of

(a)  16

(b) 12

(c)  8

(d) 4

α - particles of energy 400 KeV are bombarded on nucleus of  . In scattering of α - particles, its minimum distance from nucleus will be

(a) 0.59 nm

(b) 0.59 Å

(c) 5.9 pm

(d) 0.59 pm

Two transparent slabs have the same thickness as shown. One is made of material A of refractive index 1.5. The other is made of two materials B and C with thickness in the ratio 1 : 2. The refractive index of C is 1.6. If a monochromatic parallel beam passing through the slabs has the same number of waves inside both, the refractive index of B is

(a) 1.1

(b) 1.2

(c) 1.3

(d) 1.4

The spectra used to identify the elements in the mixture is:

In the diagram, three point charges (labeled 1, 2 and 3) are shown, along with the electric field around them. Which charge(s) is/ are positive?

The working of dynamo is based on principle of

(a) Electromagnetic induction	(b) Conversion of energy into electricity
(c) Magnetic effects of current	(d) Heating effects of current

Carbon, silicon and germanium have four valence electrons each. At room temperature the appropriate statement is:

In a cathode ray tube, what is the effect on the beam of particles if a hotter filament is used?