Mix Test

Result

Mix Test - 4

Score
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out of -
Rank
-
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TIME Taken - -

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Weekly Quiz Competition

Question 1
1 / -0

In the given circuit, what is the equivalent resistance between the points A and B (in ohms)?

A
9

B
11.6

C
14.5

D
21.2

Solution
Question 2
1 / -0

A ball of mass 0.6 kg attached to a light inextensible string rotates in a vertical circle of radius 0.75 m. It has a speed of 5 ms^-1 when the string is horizontal. Tension in string, when it is horizontal on the other side, is
(Take g = 10 ms^-2)

A
30 N

B
26 N

C
20 N

D
6 N

Solution
Question 3
1 / -0

If the radius of Earth suddenly decreases to 80% of its present value (the mass of Earth remaining the same), then the value of acceleration due to gravity will

A
remain unchanged

B
become (9.8 0.8) ms^-2

C
increase by 36%

D
increase by about 56%

Solution
Question 4
1 / -0

An electric bulb has a rating of 100 W, 200 V. If the supply voltage drops to 100 V, then what is the total heat and light energy produced by the bulb in 20 minutes?

A
10 kJ

B
20 kJ

C
30 kJ

D
40 kJ

Solution

The resistance of the filament of the bulb is,

The total energy produced, in time t = 20 60 = 1200 s, when the voltage drops to V, is

W = 3 10⁴ J = 30 kJ
Question 5
1 / -0

In a common base circuit of a transistor, the current amplification factor is 0.95. What is the base current when emitter current is 2 mA?

A
0.1 mA

B
0.6 mA

C
1 mA

D
10 mA

Solution

Current gain of common base circuit,

A

A

A

A

Or, 0.1 mA
Question 6
1 / -0

If and are non-zero vectors which obey the relation , then the angle between them is

A
0°

B
60°

C
90°

D
120°

Solution
Question 7
1 / -0

The dimensions of entropy are

A
M⁰L^–1T⁰K

B
M⁰L^–2T⁰K²

C
MLT^–2K

D
ML²T^–2K^–1

Solution

Entropy S is defined by the relation

where dS is the change in entropy, dQ is the change in heat energy and T is the absolute temperature.
Dimensions of entropy

ML²T^–2K^–1
Question 8
1 / -0

An object, a convex lens of focal length 20 cm and a plane mirror are arranged as shown in the figure given below. How far behind the mirror is the final image formed?

A
20 cm

B
30 cm

C
40 cm

D
50 cm

Solution

Given u = – 12 cm and f = + 20 cm

Using lens formula

So v = – 30 cm, i.e. the image is formed at a distance of 30 cm from the lens on the same side as the object or image is formed at 40 cm from the mirror.
Question 9
1 / -0

A circuit has a self-inductance of 1 H and carries a current of 2 A. To prevent sparking when the circuit is broken, a capacitor which can withstand 400 volts is used. The least capacitance of the capacitor connected across the switch must be equal to

A
12.5 F

B
25 F

C
50 F

D
100 F

Solution

The least capacitance is such that the energy stored in the capacitor is equal to that stored in the inductor, i.e.

Hence the correct choice is (2).
Question 10
1 / -0

The ratio of the intensities of the maxima and minima in an interference pattern is 49 : 9. What is the ratio of the intensities of the two coherent sources employed in the interference experiment?

A
7 : 3

B
49 : 9

C
5 : 2

D
25 : 4

Solution
Question 11
1 / -0

The angular amplitude of a simple pendulum is θ₀. What will be the maximum tension in its string?

A
mg(1 - θ₀)

B
mg(1 + θ₀)

C
mg(1 - θ₀²)

D
mg(1 + θ₀²)

Solution
Question 12
1 / -0

At a given volume and temperature, the pressure of a gas

A
varies inversely as its mass

B
varies inversely as the square of its mass

C
varies linearly as its mass

D
is independent of its mass

Solution

At a given volume and temperature, the pressure of a gas is directly proportional to the mass.
Question 13
1 / -0

The wavelength of de Broglie waves associated with an electron (mass m, charge e) accelerated through a potential difference of V is given by (h is Planck's constant)

A

B

C

D

Solution
Question 14
1 / -0

The moment of inertia of a thin rod of mass M and length L about an axis passing through the point at a distance L/4 from one of its ends and perpendicular to the rod is

A

B

C

D

Solution
Question 15
1 / -0

A charge q is placed at the centre of the line joining two equal charges Q. The system of three charges will be in equilibrium, if q is equal to

A

B

C

D

Solution

The three charges will be in equilibrium, if no net force acts on each charge. The charge q is in equilibrium because the forces exerted on q by charge Q at A and charge Q at B are equal and opposite. The charge Q at A will be in equilibrium, if the forces exerted on it by charge q and charge Q at B are equal and opposite, i.e. if

q = -Q/4
Similarly, charge Q at B will be in equilibrium, if q = -