moving charges and magnetism

Question 1

. State Ampere’s Circuital theorem

Answer 1

The line integral of magnetic field over a closed loop is equal to 𝜇0
times the total current passing through the surface

Question 2

state biot saravat law

Answer 2

The magnetic field at a point due to a small
element of a current carrying conductor is
directly proportional to the current (I) ,
the length of the element ⅆ𝑙 , sine of the
angle between r and ⅆ𝑙 and inversely
proportional to the square of the distance r.

Question 3

magnetic field unit

Answer 3

TESLA

Question 4

Write the principle of a moving coil galvanometer

Answer 4

a coil carrying current and placed in an external magnetic field experiences a magnetic torque.

Question 5

Explain the working of a moving coil galvanometer

Answer 5

Torque on the coil due to current
τ = NI AB————–(1)
The counter torque in the spring,
τ = kϕ —————–(2)
where k is the torsional constant of the spring; i.e. the restoring torque per
unit twist.
In equilibrium, kϕ = NI AB ————-(3)
𝛟 = (
𝐍 𝐀𝐁
𝐤
) 𝐈
𝛟 ∝ I
Thus the deflection produced in the coil is directly proportional to the
current through the coil.

Question 6

What is current sensitivity of the galvanometer

Answer 6

Current sensitivity of the galvanometer is defined as the deflection per unit
current.

Current sensitivity can be increased by increasing the number of turns N.

Question 7

What is voltage sensitivity of the galvanometer?

Answer 7

Voltage sensitivity of the galvanometer is defined as the deflection per unit
voltage

Question 8

Increasing the current sensitivity may not necessarily increase the
voltage sensitivity

Answer 8

If N → 2N, i.e., we double the number of turns, then current sensitivity,

ϕ/I= (2NAB/k) →2ϕ/I
Thus, the current sensitivity doubles.

If N → 2N, then R → 2R then the voltage sensitivity,

ϕV= (2NAB/k2R)= (NABk)1R= ϕV
Thus, the voltage sensitivity remains unchanged.

Question 9

.How will you convert a galvanometer to ammeter?

Answer 9

To convert a Galvanometer to an Ammeter ,a small resistance , called shunt
resistance S ,is connected in parallel with the galvanometer coil.

Question 10

How will you convert a galvanometer to voltmeter?

Answer 10

To convert a Galvanometer to a volteter a high resistance , R is connected
in series with the galvanometer coil