Physics - Online Test

Q1.

A jet plane is travelling towards west at a speed of 1800 km/h. If the Earth’s magnetic field at the location has a magnitude of  and the dip angle is , voltage difference developed between the ends of the wing having a span of 25 m is approximately


Answer : Option D
Explaination / Solution:


V = Vertical component of magnetic field


Q2.
Suppose that the electric field part of an electromagnetic wave in vacuum is E = {(3.1 N/C) cos [(1.8 rad/m) y + (5.4  rad/s)t]} i . Wavelength , frequency ν and the amplitude of the magnetic field part of the wave are

Answer : Option D
Explaination / Solution:
No Explaination.


Q3.
When an electron enters a magnetic field of 0.01 T with a speed of  it describes a circle of radius 6 mm there. Then specific charge of the electron is given by

Answer : Option B
Explaination / Solution:

evB=mv2rem=vrB=1076×103×0.01=1.67×1011CKg1
Q4. Sky wave propagation is possible in the range from
Answer : Option B
Explaination / Solution:
No Explaination.


Q5. A cyclist is riding with a speed of 27 km/h. As he approaches a circular turn on the road of radius 80 m, he applies brakes and reduces his speed at the constant rate of 0.50 m/s every second. What is the magnitude and direction of the net acceleration of the cyclist on the circular turn?
Answer : Option C
Explaination / Solution:

Speed of the cyclist, v = 27 km/h = 7.5 m/s
Radius of the circular turn, r = 80 m
Centripetal acceleration is given as:
ac =  0.7 ms-2

The situation is shown in the given figure:

Suppose the cyclist begins cycling from point P and moves toward point Q. At point Q, he applies the breaks and decelerates the speed of the bicycle by 0.5 m/s2.

This acceleration is along the tangent at Q and opposite to the direction of motion of the cyclist.
Since the angle between ac and aT is 900, the resultant acceleration a is given by:
a = 
0.74 = 0.86 ms-2

tan θ = 
where θ is the angle of the resultant with the direction of velocity.
tan θ = = 1.4
θ = tan-1(1.4) = 54.56° with the direction of velocity


Q6. Two insulated charged copper spheres A and B have their centres separated by a distance of 50 cm. What is the mutual force of electrostatic repulsion if the charge on each is The radii of A and B are negligible compared to the distance of separation.
Answer : Option B
Explaination / Solution:



Q7.
A specimen of oil having an initial volume of 600 is subjected to a pressure increase of 3.6   Pa and the volume is found to decrease by 0.45  what is the bulk modulus of the material?
Answer : Option B
Explaination / Solution:
No Explaination.


Q8.

A 1.0-mol sample of an ideal gas is kept at 0.0C during an expansion from 3.0 L to 10.0 L. How much work is done by the gas during the expansion?


Answer : Option B
Explaination / Solution:

In isothermal process


Q9. A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. What series of wavelengths will be emitted?
Answer : Option C
Explaination / Solution:
No Explaination.


Q10.

A man of mass 70 kg stands on a weighing scale in a lift which is moving upwards with a uniform acceleration of 5 m  what would be the reading on the scale?


Answer : Option D
Explaination / Solution:

When the lift moves upward with acceleration = 5 ms-2 the net force acting upward


R = 1050 N

(We experience weight due to reaction)

therefore Apparent weight =