CBSE 12TH PHYSICS - Online Test
Q1.
If Vm and Im are peak voltage and current, Impedance Z in an AC circuit is
Answer : Option D
Explaination / Solution:
Impedance refers to the overall obstruction offered by a circuit containing different components to the passage of current. Also Z has unit same as resistance.
So, drawing an analogy with the ohm's law, we get the above relation
Q2. For a one dimensional electric field the correct relation of and potential V is
Answer : Option B
Explaination / Solution:
Electric field is defined as the negative gradient of the potential. The potential decreases in the direction of the electric field.
Q3. Optical fibre communication uses the principle of
Answer : Option B
Explaination / Solution:
No Explaination.
Q4. Nuclides with same neutron number N but different atomic numbers Z are called
Answer : Option B
Explaination / Solution:
Two nuclides are isotones if they have the same neutron number N, but different proton number Z. For example, boron-12 and carbon-13 nuclei both contain 7 neutrons, and so are isotones .
Q5. cyclotron frequency of a charged particle having charge q and mass m in a cyclotron producing magnetic field B is
Answer : Option B
Explaination / Solution:
A particle of charge q moving with a speed v on entering a magnetic field B, experiences magnetic Lorentz force which acts as a centripetal force.
here, is the cyclotron frequency.
here, is the cyclotron frequency.
Q6. A battery is connected with a potentiometer wire. The internal resistance of the battery is negligible. If the length of the potentiometer wire of the same material and radius is doubled then
Answer : Option B
Explaination / Solution:
Potential gradient Is given by V/l. If V and l are constant, the potential gradient also remains constant. The change in the radius will cause a change in the current. This does not change the potential gradient.
Q7. Two sources of light are coherent if they have
Answer : Option A
Explaination / Solution:
No Explaination.
Q8. considering the magnetic field of the earth,the correct relation of the geographic pole and the magnetic poles is
Answer : Option A
Explaination / Solution:
No Explaination.
Q9. in n-type semiconductor majority carriers and minority carriers are respectively
Answer : Option B
Explaination / Solution:
N-type semiconductors have a larger electron concentration than hole concentration. The term n-type comes from the negative charge of the electron.
In n-type semiconductors, electrons are the majority carriers and holes are the minority carriers.
N-type semiconductors are created by doping an intrinsic semiconductor with donor impurities (or doping a p-type semiconductor as done in the making of CMOS chips). A common dopant for n-type silicon is phosphorus.
Q10. Magnitude of the electric and the magnetic fields in an plane electromagnetic wave are related by
Answer : Option B
Explaination / Solution:
No Explaination.
