Mix Test

Result

Mix Test - 6

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Weekly Quiz Competition

Question 1
1 / -0

What is the equivalent resistance across A and B?

A
2

B
3

C
4

D
5

Solution

As it is a balanced wheatstone bridge so no current will flow from 10 ohm resistor.
The equivalent resistance across A and B = 8/2 = 4 ohm
Question 2
1 / -0

A block of mass 2 kg is placed on the surface of a trolley of mass 20 kg, which is on a smooth surface. The coefficient of friction between the block and the surface of the trolley is 0.25. If a horizontal force of 2 N acts on the block, then the acceleration of the system (in ms^-2) is (Take g = 10 ms^-2)

A
1.80

B
1.00

C
0.90

D
0.09

Solution
Question 3
1 / -0

The escape velocity from the Earth is v_e. What is the escape velocity from a planet whose radius is twice that of the Earth and mean density is the same as that of the Earth?

A
v_e/2

B
v_e

C
2v_e

D
4v_e

Solution
Question 4
1 / -0

Two wires with the same dimensions and resistivities ₁ and ₂ are connected in series. The equivalent resistivity of the combination is

A

B

C

D

Solution
Question 5
1 / -0

A receiving station on the ground is receiving a signal of frequency 5 MHz from a transmitter at a height of 300 m above the surface of Earth (radius = 6.4 10⁶m) at a distance of 100 km from the receiver. The signal is coming via

A
ground wave propagation

B
sky wave propagation

C
both ground wave and sky wave propagation

D
neither ground wave nor sky wave propagation

Solution

For ground wave propagation, the maximum range is:
d_max = =
62 10³ m 62 km, which is less than 100 km.
Hence, choice (1) is wrong. The maximum frequency which can be propagated via sky waves is:
v_max = 9 MHz, which is more than 5 MHz.
Hence, a 5 MHz signal can be propagated via sky waves, and not via ground waves.
Question 6
1 / -0

Two bullets A and B are fired from a gun with the same speed, but at angles 30^oand 60^o to the horizontal, respectively. Which of the following statements is correct?

A
Bullet A will have a longer horizontal range.

B
Bullet B will have a longer horizontal range.

C
The horizontal range of bullet B will be half of that of bullet A.

D
Both the bullets will have the same horizontal range.

Solution

Ranges will be the same for the angles of projection and .
If , then .
Question 7
1 / -0

The SI unit of the universal gas constant R is

A
erg K^–1 mol^–1

B
watt K^–1 mol^–1

C
newton K^–1 mol^–1

D
joule K^–1 mol^–1

Solution

R = Since the product PV has the same unit as that of work, the unit of R is
Question 8
1 / -0

Two glasses have dispersive powers in the ratio 2 : 3. These glasses are used in the manufacturing of an achromatic objective of focal length 20 cm. What are the respective focal lengths of the two lenses of the objective?

A
6.67 cm, –10 cm

B
7.5 cm, –12.5 cm

C
9.67 cm, –15 cm

D
12.5 cm, –20 cm

Solution
Question 9
1 / -0

In an AC circuit, the potential differences across an inductance and a resistance connected in series are 16 V and 20 V, respectively. The total potential difference across the circuit is

A
20.0 V

B
25.6 V

C
31.9 V

D
53.5 V

Solution

Since the voltage leads the current by a phase angle of 90°, then potential difference across this circuit is
V = (V²_R + V²_L)^1/2 = (20 x 20 + 16 x 16)^1/2 = 25.6 V,
which is choice (2).
Question 10
1 / -0

In Young's double slit experiment, the two slits act as coherent sources of equal amplitude A and of wavelength . In another experiment with the same set up, the two slits are sources of equal amplitude A and wavelength ^_, but are incoherent. The ratio of the intensity of light at the midpoint of the screen in the first case to that in the second case is

A
1 : 1

B
1 : 2

C
2 : 1

D
: 1

Solution
Question 11
1 / -0

A person measures the time period of a simple pendulum inside a stationary lift and finds it to be T. If the lift starts accelerating upwards with an acceleration of g/3, then the time period of the pendulum will be

A

B

C

D

Solution
Question 12
1 / -0

2 cylindrical rods of lengths l₁ and I₂and radii r₁ and r₂ have thermal conductivities k₁ and k₂, respectively. The ends of the rods are maintained at the same temperature difference. If l₁ = 2I₂ and r₁ = r₂/2, then the rate of heat flow in them will be the same, if k₁/k₂ is equal to

A
1

B
2

C
4

D
8

Solution

The rate of heat flow in rods A and B is

Hence, the correct choice is (4).
Question 13
1 / -0

A radio transmitter operates on a wavelength of 1500 m at a power of 400 kilowatt. The energy of the radio photon (in joules) is

A
1.32 x 10^-34 J

B
1.32 x 10^-28 J

C
1.32 x 10^-36 J

D
1.32 x 10^-32 J

Solution
Question 14
1 / -0

A uniform rod of length L is suspended from one end such that it is free to rotate about an axis passing through that end and perpendicular to the length. What minimum speed must be imparted to the lower end, so that the rod completes one full revolution?

A

B

C

D

Solution
Question 15
1 / -0

A charge having magnitude Q is divided into parts q and (Q – q), which are held at a certain distance r apart. The force of repulsion between the two parts will be maximum, if the ratio q/Q is

A

B

C

D

Solution