Question

Tangent galvanometer measures

• A. capacitance
• B. current
• C. resistance
• D. potential difference

Answer 1

Answer: (B)

When a current is passed through the galvanometer coil, then a magnetic field $B$ is produced at right angles to the plane of the coil, ie, at right angles to the horizontal component of earth's magnetic field $H$. Under the influence of two crossed magnetic fields $B$ and $H,$ the magnetic needle of galvanometer
undergoes a deflection $\theta$ which is given by the tangent law. Using tangent law, we can find a relation
$I\propto \tan \theta$
Which clearly indicates that tangent galvanometer is an instrument used for detection of electric current in a circuit.
Note A tangent galvanometer is most accurate when its deflection is $45^{\circ }$