7 Which of the following is NOT true of experiments involving curved mirrors?
image distance is negative for for real image
object distance is positive
image distance is negative for virtual image
focal length is negative for convex mirrors
8 The null condition in potentiometer experiment shows that
the potential difference under test is zero
current is varying in the circuit
current is increasing in the circuit
potential differences are balanced
9 The potentiometer wire plays equivalent role of which of these devices in a circuit?
rheostat
thermostat
galvanometer
ammeter
