Physics - Online Test
Q1. A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is and points radially inward, what is the net charge on the sphere?
Answer : Option D
Explaination / Solution:
Since the electric field is inwards so charge is negative.
Since the electric field is inwards so charge is negative.
Q2. A piece of copper having a rectangular cross-section of 15.2 mm 19.1 mm is pulled in tension with 44,500 N force, producing only elastic deformation. Calculate the resulting strain? Take Young's modulus of copper as 11 Pa
Answer : Option C
Explaination / Solution:
No Explaination.
Q3. A sample of ideal gas is expanded to twice its original volume of 1.00 in a quasi-static process for which with . How much work is done by the expanding gas?
Answer : Option D
Explaination / Solution:
P=αV2α=5.00×1.01×105Vi=1.00m3Vf=2.00m3W=∫1.002.00P.dV=∫1.002.00αV2.dV=[αV33]2.001.00=1.18MJ
Q4. Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. a horizontal force F = 600 N is applied to the 20 kg mass so as to pull it. What is the tension in the string?
Answer : Option D
Explaination / Solution:
Let,
T =tension in the string,
a= acceleration in the direction of force F.
m1=10 kg and m2= 20 kg
Therefore,common acceleration
Now the tension T in the string is
Q5. According to Ohm's law
Answer : Option C
Explaination / Solution:
Ohm’s law states I is proportional to V.
This holds good at steady temperatures and for the flow of constant current.
Q6.
A trolley of mass 200 kg moves with a uniform speed of 36 km/h on a frictionless track. A child of mass 20 kg runs on the trolley from one end to the other (10 m away) with a speed of 4 m relative to the trolley in a direction opposite to the its motion, and jumps out of the trolley. What is the final speed of the trolley?
Answer : Option D
Explaination / Solution:
Mass of troly M = 200Kg
mass of child m = 20Kg
speed of trolley v = 36Km/hr=36 x 5/18 = 10m/s
Let v' be the final velocity of the trolley with respect to the ground.
Final velocity of the boy with respect to the ground =
from conservation of linear momentum
Q7. In which model is it completely wrong to ignore multiple scattering for the calculation of average angle of scattering of αα -particles by a thin foil?
Answer : Option D
Explaination / Solution:
No Explaination.
Q8. The magnitude of the electric field in the annular region of a charged cylindrical capacitor
Answer : Option D
Explaination / Solution:
the electric field at point distance r from the axis of the capacitor and located in the annular region (the region between the two cylinders) of a cylindrical capacitor with linear charge density λ is given by
This field is higher near the inner cylinder.
This field is higher near the inner cylinder.
Q9. The difference between nuclear forces and electromagnetic forces is that
Answer : Option A
Explaination / Solution:
The nuclear force does not depend upon the charge of nucleons.Nuclear forces usually depend upon the velocity of the nucleons.
Q10. What is the moment of inertia of a thin rod of length L and mass M about an axis passing through one end and perpendicular to its length?
Answer : Option D
Explaination / Solution:
Using theorem of parallel axis, the axis is shifted by L/2 distance from centre of Mass where the Moment of Inertia is ML2/12, thus the moment of inertia of a thin rod about an axis passing through one end and perpendicular to its length is ML2/12 + ML2/4 =
