Free download in PDF CBSE Class 12 Physics Short Questions & Answers. Here Gkseries provide Physics Solve Questions and Answers for CBSE Class 12 Students.
41
For measurement of potential difference, a potentiometer is preferred over voltmeter because
A
potentiometer does not take current from the circuit.
B
potentiometer is cheaper than voltmeter.
C
the resistance of potentiometer is less than voltmeter.
Answer: The battery of potentiometer can have a voltage of 15 V and R adjusted so that the potential drop across the wire slightly exceeds 10 V.
44
A resistance R is to be measured using a meter bridge. Student chooses the standard resistance S to be 100 Ω He finds the null point at l1 = 2.9 cm. He is told to attempt to improve the accuracy. Which of the following is a useful way? [NCERT Exemplar]
A
He should measure l1 more accurately.
B
He should change Sto 1000 Ω and repeat the experiment.
C
He should change S to 3 Ω and repeat the experiment.
D
He should give up hope of a more accurate measurement with a meter bridge.
Answer: He should change S to 3 Ω and repeat the experiment.
45
Consider a current carrying wire current I in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while die current/remain unaffected. The agent that is essentially responsible for is
A
source of emf.
B
electric field produced by charges accumulated on the surface of wire.
C
the charges just behind a given segment of wire which push them just the right way by repulsion.
Answer: The charged particles and ions in cyclotron can move on any arbitrary path.
47
A charged particle is moving in a cyclotron, what effect on the radius of path of this charged particle will occur when the frequency of the ratio frequency field is doubled?
48
Two a-particles have the ratio of their velocities as 3 : 2 on entering the field. If they move in different circular paths, then the ratio of the radii of their paths is
49
A charged particle is moving on circular path with velocity v in a uniform magnetic field B, if the velocity of the charged particle is doubled and strength of magnetic field is halved, then radius becomes
56
A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field B, such that B is perpendicular to the plane of the loop. The magnetic force acting on the loop is
59
The maximum current that can be measured by a galvanometer of resistance 40 Ω is 10 mA. It is converted into voltmeter that can read upto 50 V. The resistance to be connected in the series with the galvanometer is
