For measurement of potential difference, a potentiometer is preferred over voltmeter because
Answer: potentiometer does not take current from the circuit.
Which of the following is wrong? Resistivity of a conductor is
Answer: independent of temperature.
Two cells of emf’s approximately 5 V and 10 V are to be accurately compared using a potentiometer of length 400 cm. [NCERT Exemplar]
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.
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]
Answer: He should change S to 3 Ω and repeat the experiment.
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
Answer: electric field produced by charges accumulated on the surface of wire.
Which of the following is not correct about cyclotron?
Answer: The charged particles and ions in cyclotron can move on any arbitrary path.
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?
Answer: It will remain unchanged.
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
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
Which one of the following is correct statement about magnetic forces?
Answer: Magnetic forces do not obey Newton’s third law.
In an inertial frame of reference, the magnetic force on a moving charged particle is Its value in another inertial frame of reference will be
Answer: changed due to change in velocity of charged particle
A strong magnetic field is applied on a stationary electron. Then the electron
Answer: remained stationary.
A positive charge enters in a magnetic field and travels parallel to but opposite the field. If experiences
Answer: an accelerated force.
An electron is projected along the axis of a circular conductor carrying the same current. Electron will experience
Answer: no force experienced.
The gyro-magnetic ratio of an electron in an H-atom, according to Bohr model, is
Answer: independent of which orbit it is in.
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
If the beams of electrons and protons move parallel to each other in the same direction, then they
Answer: repel each other.
A current loop placed in a non-uniform magnetic field experiences
Answer: a force and a torque.
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
A current carrying closed loop of an irregular shape lying in more than one plane when placed in uniform magnetic field, the force acting on it