Electricity and Magnetism - SS2 Physics Past Questions and Answers - page 1
Which of the following statements correctly describes an electric field?
It is a scalar quantity.
It is a vector quantity
It depends on the magnitude of the charge only
It is always directed towards the positive charge.
The electric field lines around a positive point charge:
Originate from the charge and terminate at infinity
Originate from infinity and terminate at the charge
Originate from the charge and continue indefinitely
Originate from infinity and continue indefinitely.
The electric potential at a point in an electric field is:
A measure of the electric field strength at that point
The work done in bringing a unit positive charge from infinity to that point
The ratio of the electric field strength to the charge at that point
The ratio of the charge to the distance from the point charge.
The electric potential inside a conductor in electrostatic equilibrium is:
Zero
Non-zero and constant
Increasing as the distance from the centre of the conductor increases
Decreasing as the distance from the centre of the conductor increases.
Two point charges, +Q and -Q, are placed at a distance d from each other. The electric potential at the midpoint between the charges is:
Zero
Positive
Negative
Indeterminate.
Two point charges, +3 μC and -5 μC, are placed 10 cm apart. What is the magnitude of the electric field at a point that is 5 cm from the positive charge?
To calculate the electric field, we can use Coulomb's law:
Electric field (E) = (k x |q|) / r2, where k is the electrostatic constant, q is the charge, and r is the distance.
Substituting the values, we have:
E = (9 x 109 Nm2/C2 x 3 x 10-6 C) / (0.05 m).
E ≈ 1.08 x 105 N/C
A parallel plate capacitor has a capacitance of 12 μF. If a potential difference of 24 V is applied across the plates, what is the charge stored on the capacitor?
The charge stored on a capacitor can be calculated using the formula:
Q = C x V, where Q is the charge, C is the capacitance, and V is the potential difference.
Plugging in the values, we have:
Q = 12 x 10-6 F x 24 V
Q = 2.88 x 10-4 C
A positive charge of +6 μC is placed in an electric field where the electric potential is 120 V. What is the change in electric potential energy if the charge is moved 4 cm in the direction opposite to the electric field?
The change in electric potential energy can be calculated using the formula:
ΔPE = q x ΔV, where ΔPE is the change in potential energy, q is the charge, and ΔV is the change in potential.
Plugging in the values, we have:
ΔPE = 6 x 10-6 C x (-120 V)
ΔPE = -7.2 x 10-4 J
A point charge of +2 nC is placed at the origin. What is the electric potential at a point located 4 m away from the charge?
The electric potential can be calculated using the formula:
V = (k x q) / r, where V is the potential, k is the electrostatic constant, q is the charge, and r is the distance.
Plugging in the values, we have:
V = (9 x 109 Nm2/C2 x 2 x 10-9 C) / 4 m
V = 4.5 x 103 V
The capacitance of a capacitor depends on:
Charge stored on the capacitor
Voltage across the capacitor
Physical dimensions of the capacitor
All of the above