# Tangent Galvanometer Viva Questions

**Tangent Galvanometer Experiment Viva Questions**

*(1) What is meant by a tangent galvanometer? *

A tangent galvanometer is a moving magnet type galvanometer and is used for measuring strength of electric current.

*(2) What is tangent law? *

If B_{h} and B be two magnetic fields acting
perpendicular to each other, and their resultant makes an angle θ
with B_{h},

tan θ = (B/B_{h});

Therefore, B = B_{h} tan θ

*(3) What is magnetic meridian? *

Magnetic meridian is a vertical plane passing through the magnetic axis (axial line) of a freely suspended or pivoted magnetic needle.

*(4) Why is the pointer long and made of aluminium? *

Aluminium makes pointer light. Moreover, aluminium is non-magnetic.

*(5) What is the function of the plane mirror at the bottom of
the compass box? *

It helps in reading the position of the pointer on the scale without error of parallax.

*(6) Define reduction factor of T.G. *

Reduction factor of T.G. is defined as that current which when passed through the galvanometer required to produce a deflection of 45° when set in magnetic meridian.

*(7) What are the two perpendicular magnetic fields in T.G.
experiment? *

The horizontal component of earth's magnetic field and the field produced by the current carrying circular coil.

*(8) Why the deflection in tangent galvanometer is preferred to
be nearly 45°? *

An error in the measurement of θ will affect the result as tangent of θ. When θ is nearly 45° the variation in tan θ is very small and hence a small error in measurement of θ will cause negligible error.

*(9) Aim of Tangent Galvanometer Experiment*

*(10) Apparatus of Tangent Galvanometer Experiment*

*(11) Theory of Tangent Galvanometer Experiment*

_{h}, the earth horizontal intensity at the place, then according to the tangent law, B = B

_{h}tan θ; where θ is the mean deflection in the TG.

_{h}tan θ

^{-7}x 2πni/r = B

_{h}tan θ

^{7}x B

_{h}r/2πn) x tan θ ; i = K tan θ ; where K is called the reduction factor of TG.

^{7}x B

_{h}r)/2πn

_{h}= (2πnK/r) x 10

^{-7}

*(12) Procedure of Tangent Galvanometer Experiment*

**Preliminary adjustments**

**To find the reduction factor K of TG**

_{1}and θ

_{2}at both ends of the pointer are noted. The current is reversed with the help of the commutator. Again the readings θ

_{3}and θ

_{4}of the pointer are taken. The average of the four readings gives θ, the deflection of T.G. The reduction factor K of the T.G is calculated from the equation.

**To calculate the horizontal intensity B**

_{h}at the place**B**

_{h}= 2πnK x 10^{-7}/r
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