Explain how a galvanometer works and what it is used for. Answer with at
least two complete sentences.

When a coil is placed in a magnetic field and current is passed through it, the coil experiences a deflecting torque (called ‘The Motor Principle’) This is due to the interaction of the fields (owing to current and magnet). The magnitude of deflection is the measure of current.

Explanation:

When a current is passed through the coil of Galvanometer, it starts rotating due to a deflecting couple, that arises due to the interaction of fields of magnet and current. The turning coil twists the suspension strip and comes to rest. The torque due to couple exerted by magnetic field is balanced by an opposing couple due to the reaction of twisted suspension strip, called Controlling Couple or  Elastic Restoring Torque. A pointer is attached to the coil, which gives the reading of current on a calibrated scale.

A labelled diagram for the parts of galvanometer is given in the attachment

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s