JEE Main Test 139

Result

JEE Main Test 139

Score
-
out of -
Rank
-
out of -

TIME Taken - -

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Weekly Quiz Competition

Question 1
4 / -1

In a ∆PQR, if 3 sin P + 4 cos Q = 6 and 4 sin Q + 3 cos P = 1, then ∠R is equal to

A
5π/6

B
π/6

C
π/4

D
3π/4

Solution
Question 2
4 / -1

A pendulum bob carries a negative charge – q. A positive charge +q is held at the point of support. Then, the time period of the bob is

A

B

C

D

Solution

Restoring force is not changed as electrostatic forces are central forces. Negative and positive charges are at the two extremeties of the string affect tension T which does not affect the restoring force.
Question 3
4 / -1

A whistle of frequency 540 Hz rotates in a horizontal circle of radius 2 mat an angular speed of15 rads ^-1. The highest frequency heard by a listener at rest with respect to the centre of circle
(velocity of sound in air = 330 ms ^-1)

A
590 Hz

B
594 Hz

C
598 Hz

D
602 Hz

Solution
Question 4
4 / -1

A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor

A
decreases

B
remains unchanged

C
becomes infinite

D
increases

Solution
Question 5
4 / -1

A certain current on passing through a galvanometer produces a deflection of 100 divisions. When a shunt of one ohm is connected, the deflection reduces to 1 division. The galvanometer resistance is

A
100Ω

B
99Ω

C
10Ω

D
9.9Ω

Solution
Question 6
4 / -1

A step-down transformer is used on a 1000 V line to deliver 20 A at 120 V at the secondary coil. If the efficiency of the transformer is 80%, the current drawn from the line is

A
3 A

B
30 A

C
0.3 A

D
2.4 A

Solution
Question 7
4 / -1

Quantity that remains unchanged in a transformer is

A
voltage

B
current

C
frequency

D
None of these

Solution

Transformer does not change the frequency of input AC.
Question 8
4 / -1

A horizontal straight wire 20 m long extending from East to West is falling with a speed of 5.0 ms^-1 , at right angles to the horizontal component of the earth's magnetic field 0.030 ×10^-4 Wbm^-2 . The instantaneous value of the emf induced in the wire will be

A
6.0 mV

B
3 mV

C
4.5 mV

D
1.5 mV

Solution
Question 9
4 / -1

An electromagnetic wave is propagating along x-axis. At x = 1cm and t =10 s, its electric vector |E| = 6 V/m, then the magnitude of its magnetic vector is

A
2 × 10^-8

B
3 × 10^-7

C
6 × 10^-8

D
5 × 10^-7

Solution
Question 10
4 / -1

A plane EM wave travels in free space along X-axis. At a particular point in space, the electric field along Y-axis is 9.3 Vm ^-1. The magnetic induction is

A
3.1 × 10^-8 T

B
3 × 10^-5 T

C
3 × 10^-6 T

D
9.3 × 10^-6 T

Solution