CBSE 12TH PHYSICS - Online Test
Q1. A rectangular conductor PQRS in which the conductor PQ is free to move is kept in a magnetic field B ,which is perpendicular to the PQRS which lies in a single plane. If the conductor PQ of length l is pushed by a force F then the power supplied is (assuming a circuit ressistance r)
Answer : Option D
Explaination / Solution:
P = Fv
Q2. In interaction of radiation with matter, radiation behaves as if it is made up of particles called
Answer : Option C
Explaination / Solution:
Photon is the small packet of energy. Rest mass of photon is zero but its kinetic mass is not zero. The photon travels with the speed of light.
Q3. In Digital type signals, signals can take
Answer : Option D
Explaination / Solution:
No Explaination.
Q4. The unit of charge is
Answer : Option C
Explaination / Solution:
The SI unit of quantity of electric charge is the coulomb, which is equivalent to about 6.242×1018 e (e is the charge of a proton).
Hence, the charge of an electron is approximately −1.602×10−19 C. The coulomb is defined as the quantity of charge that has passed through the cross section of an electrical conductor carrying one ampere within one second. The symbol Q is often used to denote a quantity of electricity or charge.
Q5. To produce an emission spectrum of hydrogen
Answer : Option D
Explaination / Solution:
No Explaination.
Q6. For a series LCR circuit the input impedance at resonance
Answer : Option C
Explaination / Solution:
Impedance in series LCR circuit
at resonance
Q7. The electric dipole potential falls off, at large distance r
Answer : Option D
Explaination / Solution:
The potential due to a dipole at a point (r ,θ)from its center is therefore,
Q8. Thin lens approximation for a lens is
Answer : Option B
Explaination / Solution:
No Explaination.
Q9. The difference in mass of a nucleus and its constituents is called
Answer : Option C
Explaination / Solution:
The mass defect of a nucleus represents the mass of the energy of binding of the nucleus, and is the difference between the mass of a nucleus and the sum of the masses of the nucleons of which it is composed.
Q10. The magnetic field at the center of a solenoid coil having n turns and carrying a current I in air is
Answer : Option B
Explaination / Solution:
The magnetic field at the centre of a solenoid with air core is .where,is the permeability of free space, n the number of turns per unit length and I is the current flowing through the solenoid.
