Directions: Each question contains STATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement 1 :A transistor amplifier in common emitter configuration has a low input impedence.

Statement 2 :The base to emitter region is forward biased.

(a)Statement -1 is true, Statement-2 is true;Statement -2 is a correct explanation for Statement-1
(b)Statement -1 is true, Statement-2 is true; Statement -2 is not a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is false
(d)Statement -1 is false, Statement-2 is true

Solution

(a)Statement -1 is true, Statement-2 is true;Statement -2 is a correct explanation for Statement-1

Fevicol is added to paint to be painted on the walls, because

it increases adhesive force between paint and wall.
it decreases adhesive force between paint and wall molecules.
it decreases cohesive force between paint molecules.
None of these

DIRECTIONS: Each question contains STATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement-1 : Though light of a single frequency(monochromatic) is incident on a metal, the energies of emitted photoelectrons are different.

Statement-2 : The energy of electrons emitted from inside the metal surface, is lost in collision with the other atoms in the metal.

(a)Statement-1 is false, Statement-2 is true
(b)Statement-1 is true, Statement-2 is true; Statement-2 is a correct explanation for Statement-1
(c)Statement-1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1
(d)Statement-1 is true, Statement-2 is false 64.

Solution

(a)Statement-1 is false, Statement-2 is true

When alight of single frequency falls on the electrons of inner layer of metal, then this electron comes out of the metal surface after a large number of collisions with atom of it's upper layer.

If the kinetic energy of a body is increased by 300%, the momentum of the body is increased by

300%
200%
100%
50%

Solution

In terms of Bohr radius r₀, the radius of the second Bohr orbit of a hydrogen atom is given by

4 r₀
8 r₀
√2 r₀
2 r₀

Solution

As r α n², therefore, radius of 2nd Bohr’s orbit = 4 r₀

A composite disc is to be made using equal masses of aluminium and iron so that it has as high a moment of inertiaas possible. This is possible when

the surfaces of the disc are made of iron with aluminium inside
the whole of aluminium is kept in the core and the iron at the outer rim of the disc
the whole of the iron is kept in the core and the aluminium at the outer rim of the disc
the whole disc is made with thin alternate sheets of iron and aluminium

Solution

Density of iron > density of aluminium moment of inertia = ∫r² dm.\

∴ Since ρ_iron > ρ_aluminium

so whole of aluminium is kept in the core and the iron at the outer rim of the disc.

A metal cube of length 10.0 mm at 0°C (273K) is heated to 200°C (473K). Given :its coefficient of linear expansion is 2 × 10^-5 K^-1. The percent change of its volume is

Solution

Percentage change in volume = γt × 100

= 3α × 100 = 300 α t = 300 × 2 × 10^-5 × 200 = 1.2

In the equation X = 3YZ², X and Z are dimensions of capacitance and magnetic induction respectively. In MKSQ system, the dimensional formula for Y is

[M^-3 L^-2 T^-2 Q^-4]
[M L^-2]
[M^-3 L^-2 Q⁴ T⁸]
[M^-3 L^-2 Q⁴ T⁴]

Solution

[Y]=\(\frac{[X]}{[Z^{2}]}=\frac{M^{-1}L^{-2}T^{4}A^{2}}{M^{2}T^{-4}A^{-2}}\)=M^-3L^-2Q⁴T⁴

\(\left ( A=\frac{Q}{T} \right )\)

Direction: Each question contains STATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

(a) Statement -1 is true, Statement-2 is true;Statement -2 is a correct explanation for Statement-1

(b)Statement -1 is true, Statement-2 is true; Statement -2 is not a correct explanation for Statement-1

(c)Statement -1 is true, Statement-2 is false

(d)Statement -1 is false, Statement-2 is true

Statement 1: In a simple battery circuit, the point of the lowest potential is negative terminal of the battery.

Statement 2:The current flows towards the point of the higher potential, as it does in such a circuit from the negative to the positive terminal.

View Ans & Explanation
(c)Statement -1 is true, Statement-2 is false

Positive terminal of a battery is point of highest potential and current flows from highest to lowest potential i.e. from +ve to –ve potential.

A metallic wire of length L metre extends by ι metre when stretched by suspending a weight Mg from it. The mechanical energy stored in the wire is

2 Mg ι
Mg ι
^Mgι⁄₂
^Mgι⁄₄

Solution

Weight Mg moves the centre of gravity of the spring

through a distance \(\frac{(0+\iota )}{2}=\iota /2\)

Mechanical energy stored = Work done = Mg ι/2

The perfect gas equation for 4 gram of hydrogen gas is

PV = RT
PV = 2RT
PV=¹⁄₂ R
PV = 4RT

Solution

n=⁴⁄₂=2

The speed of sound in air under ordinary conditions is around 330 m s^–1. The speed of sound in hydrogen under similar conditions will be (in m s^–1) nearest to

330
1200
600
900

Solution

\(\frac{V_{1}}{V_{2}}=\sqrt{\frac{\rho _{2}}{\rho _{1}}}\)

Which one is correct about fission?

Approx. 0.1% mass converts into energy
Most of energy of fission is in the form of heat
In a fission of U²³⁵ about 200 eV energy is released
On an average, one neutron is released per fission of U²³⁵

If relative permeability of iron is 2000. Its absolute permeability in S.I. units is

8π × 10^–4
8π× 10^–3
800/π
8π × 10⁹/π

Solution

μ = μ₀μ_r = (4π × 10^-7) × 2000 = 8π × 10^–4 S.I. units

A particle with rest mass m₀ is moving with speed of light c.The de-B roglie wavelength associated with it will be

α
zero
m₀c/h
hv/m₀c

Solution

UnAttempted

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Attempted

0

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