Physics - Online Test
Q1. At resonance the current in an LCR circuit
Answer : Option D
Explaination / Solution:
in LCR series circuit current
at resonance
hence current will be maximum.
Q2. An equipotential surface is a surface
Answer : Option D
Explaination / Solution:
When the potential at all points on the surface is the same; such a surface is called an equipotential surface. The potential difference between any two points on an equipotential surface is zero, while the potential may be positive, negative or even zero.
Q3. Centre of gravity can be defined
Answer : Option C
Explaination / Solution:
The point at which the entire weight of a body may be thought of as centered so that if supported at this point the body would balance perfectly, so it can also be defined as as that point where the total gravitational torque on the body is zero.
Q4. At large flow velocities the flow of a fluid becomes
Answer : Option B
Explaination / Solution:
When any liquid is flowing more than the velocity of it's critical velocity then flow becomes turbulent.
Q5. The number of degrees of freedom a monatomic molecule is
Answer : Option A
Explaination / Solution:
Degrees of freedom of a system refers to the possible independent motions a system can have.
Monoatomic gas molecule can have 3 independent motion and hence have 3 degrees of freedom (all are translational).
Q6. The power P of a lens is given by the approximate formula
Answer : Option B
Explaination / Solution:
No Explaination.
Q7. Correct expression for mass defect Δm is
Answer : Option C
Explaination / Solution:
Measurements have shown that the mass of a particular atom is always slightly less than the sum of the masses of the individual neutrons, protons, and electrons of which the atom consists. The difference between the mass of the atom and the sum of the masses of its parts is called the mass defect.
Here Z is the number of protons (atomic number) and (A-Z) is the number of neutrons, A being the total number of nucleons (mass number).
Q8. Animal and plant life in lakes and ponds are not destroyed because
Answer : Option D
Explaination / Solution:
As and when water is cooled down to its freezing point the thickness T of the ice layer increases. The increase in thickness of ice decreases the rate of cooling of water and thus freezing process slows down.
Q9. The magnetic field at the center of a toroidal coil having n turns,radius r and carrying a current I in air is
Answer : Option B
Explaination / Solution:
A toroid is a solenoid wound on itself. The magnetic field exists only in the region of the hollow circular ring which has the turns of wire wound on it. Using Ampere’s circuital law,
Q10. Percentage error δa is given by
Answer : Option D
Explaination / Solution:
Percentage Error: It is the relative error measured in percentage.
So Percentage Error
%
