Which one of the following physical quantities is represented by the shaded area in the given graph?

Torque
Impulse
Power
Work done

Solution

\(Work \: done=\int Fdx\)

Four metallic plates each with a surface area of one side A,are placed at a distance d from each other. The two outer plates are connected to one point A and the two other inner plates to another point B as shown in the figure. Then the capacitance of the system is

\(\frac{\varepsilon _{0}A}{d}\)
\(\frac{2\varepsilon _{0}A}{d}\)
\(\frac{3\varepsilon _{0}A}{d}\)
\(\frac{4\varepsilon _{0}A}{d}\)

Solution

It consists of two capacitors in parallel, therefore, the total capacitance is = \(\frac{2\epsilon _{0}A}{d}\)

(The plates of B, having negative charge do not constitute a capacitor).

A gas has pressure P and volume V.It is now compressed adiabatically to 1/32 times the original volume. Given that(32)^1.4= 128, the final pressure is (γ= 1.4)

P/128
P/32
32 P
128 P

Solution

A vessel contains air at a temperature of 15º C and 60 % R.H.What will be the R.H. if it is heated to 20º C? (S.V.P. at 15º C is 12.67 & at 20º C is 17.36 mm of Hg respectively)

262 %
26.2 %
44.5 %
46.2 %

Solution

Angular momentum of a system of a particles changes, when

force acts on a body
torque acts on a body
direction of velocity changes
None of these

Solution

If we apply a torque on a body, then angular momentum of the body changes according to the relation
\(\dot{\tau }=\frac{d\dot{L}}{dt}\Rightarrow if\: \dot{\tau }=0 \: then,\vec{L}=constant\)

A sample of an ideal gas occupies a volume of V at a pressure P and absolute temperature. T. The mass of each molecule is m. The equation for density is

m k T
P/k T
P/(k T V)
P m/k T

Solution

Angular momentum is

a polar vector
an axial vector
a scalar
None of these

Solution

Angular momentum \(\dot{L}\) is defined as \(\dot{L}=\dot{r}\times m(\dot{v})\) so \(\dot{L}\) is, an axial vector..

A ball of mass 0.5 kg moving with a velocity of 2m/sec strikes a wall normally and bounces back with the same speed.If the time of contact between the ball and the wall is one millisecond, the average force exerted by the wall on the ball is :

2000 newton
1000 newton
5000 newton
125 newton

Solution

\(F=\frac{mv-(-mv)}{t}=\frac{2mv}{t}=\frac{2\times 0.5\times 2}{10^{-3}}=2\times 10^{3}N\)

A mass m fall on spring of spring constant k and negligible mass from a height h. Assuming it sticks to the pan and executes simple harmonic motion, the maximum height upto which the pan will rise is

^mg⁄_k
\(\frac{mg}{k}\left [ \sqrt{1+\frac{2kh}{mg}-1} \right ]\)
\(\frac{mg}{k}\left [ \sqrt{1+\frac{2kh}{mg}+1} \right ]\)
\(\frac{mg}{k}\left [ \sqrt{1+\frac{kh}{mg}-1} \right ]\)

Solution

The ratio of intensity of magnetisation and magnetising field is called

permeability
magnetic induction
magnetic intensity
magnetic susceptibility

Solution

IH = X_m

The relative velocity V_AB or V_BA of two bodies A & B maybe

(1)greater than velocity of body A

(2)greater than velocity of body B

(3)less than the velocity of body A

(4)less than the velocity of body B

(1) and (2) only
(3) and (4) only
(1), (2) and (3) only
(1), (2), (3) and (4)

Solution

All options are correct :

(i) When two bodies A & B move in opposite directions then relative velocity between A & B either V_AB or V_BA both are greater than V_A & V_B.

(ii) When two bodies A & B move in parallel direction

then V_AB=V_A-V_B⇒V_AB < V_A

V_BA=V_B-V_A⇒V_BA < V_B

If one mole of a monatomic gas(γ= 5/3) is mixed with one mole of a diatomic gas (γ= 7/3), the value of g for the mixture is

1.40
1.50
1.53
3.07

Solution

A simple pendulum has a length l, mass of bob m. The bob is given a charge q. The pendulum is suspended between the vertical plates of the charged parallel plate capacitor. If E is the field strength between the plates, then time period T equal to

\(2\pi \sqrt{\frac{l}{g}}\)
\(2\pi \sqrt{\frac{l}{g+\frac{qE}{m}}}\)
\(2\pi \sqrt{\frac{l}{g-\frac{qE}{m}}}\)
\(2\pi \sqrt{\frac{l}{g^{2}+(\frac{qE}{m})^{2}}}\)

An air capacitor of capacity C= 10 μF is connected to a constant voltage battery of 12 volt. Now the space between the plates is filled with a liquid of dielectric constant 5. The(additional) charge that flows now from battery to the capacitor is

120 μ C
600 μ C
480 μ C
24 μ C

Solution

q₁ = C₁V = 5 × 12 = 120 μ C

q₂ = C₂V = KC₁ × V = 5 × 10 × 12 = 120 μ C

Additional charge that flows

= q₂- q₁ = 600 - 120 = 480 μ C.

An isotropic point source S of sound emits constant power.Two points A and B separated by a distance r are situated near the source as shown in figure.The difference of the intensity level of sound at the points A and B is about

3 dB
2 dB
6 dB
12 dB

Solution

UnAttempted

0

Attempted

0

Correct

0

Wrong