(d) deflects and gradually comes to the original position in a time that is large compared to the time constant,The compass needle deflects due to the presence of the magnetic field. Inside the capacitor, a magnetic field is produced when there is a changing electric field inside it. As the cepacitor is connected across the battery, the charge on its plates at a certain time t is given by.Q=CV(1−e−5/70) whereQ= charge developed on the plates of the capacitorR= resistance of the resistor connected in series with the capacitorC= capacitance of the capacitorV= potential difference of the batteryThe time constant of the capacitor is given, τ=RC The capacitor keeps on charging up to the time τ . The development of charge on the plates will be gradual after t=RC . The change in electric field will be up to the time the charge is developing on the plates of the capacitor. Thus, the compass needle deflects and gradually comes to the original position] in a time that is large compared to the time constant.