Electricity and Magnetism - SS1 Physics Past Questions and Answers - page 2
When a capacitor is connected to a DC voltage source, it initially behaves as a:
Closed switch
Short circuit
Open switch
Resistor
When a capacitor is fully charged, the potential difference across its plates is equal to:
Zero
The supply voltage
The current flowing through it
The resistance in the circuit
Capacitors are often used in electronic circuits to:
Smooth out voltage fluctuations
Increase the circuit's resistance
Amplify the signal
Decrease the current flow
Explain the concept of capacitance and how it is related to the ability of a capacitor to store electrical energy.
Capacitance is a measure of a capacitor's ability to store electric charge. It is defined as the ratio of the magnitude of the charge stored on one of the capacitor's plates to the potential difference (voltage) across the plates. Capacitance depends on factors such as the size and shape of the capacitor, the distance between the plates, and the dielectric material used. A higher capacitance value indicates a greater ability to store charge and energy. When a capacitor is connected to a voltage source, it charges up by accumulating charge on its plates. The stored charge represents stored electrical energy that can be released when needed.
Discuss the factors that affect the capacitance of a capacitor.
The capacitance of a capacitor is affected by several factors. Firstly, the surface area of the plates plays a role. A larger plate area increases capacitance because there is more space for the charge to accumulate. Secondly, the distance between the plates affects capacitance. A smaller distance results in a higher capacitance as the electric field between the plates is stronger.
Thirdly, the dielectric material placed between the plates influences capacitance. Different dielectric materials have different dielectric constants, which affect the capacitance value. Finally, the number of plates in a capacitor also affects capacitance. Adding more plates in parallel increases the effective plate area and thus increases capacitance.
When a charged particle moves through a magnetic field, the direction of the magnetic force acting on the particle depends on:
The magnitude of the magnetic field
The charge of the particle
The velocity of the particle
All of the above
The magnitude of the magnetic force acting on a charged particle moving in a magnetic field depends on:
The charge of the particle
The velocity of the particle
The strength of the magnetic field
All of the above
The direction of the magnetic force acting on a positively charged particle moving in a magnetic field is:
In the same direction as the velocity of the particle
Opposite to the direction of the velocity of the particle
Perpendicular to the velocity of the particle
Parallel to the velocity of the particle
Explain the factors that determine the magnitude and direction of the magnetic force experienced by a charged particle moving in a magnetic field.
The magnitude and direction of the magnetic force on a charged particle depend on three factors: the magnitude of the charge (q) of the particle, the velocity (v) of the particle, and the strength and direction of the magnetic field (B). The magnitude of the magnetic force is given by the equation F = qvBsinθ, where θ is the angle between the velocity vector and the magnetic field vector. The direction of the magnetic force is perpendicular to both the velocity vector and the magnetic field vector, following the right-hand rule.
Describe the motion of a charged particle in a uniform magnetic field when it is moving parallel, perpendicular, or at an angle to the magnetic field lines.
When a charged particle moves parallel to the magnetic field lines, the magnetic force acting on it is zero since the angle between the velocity vector and the magnetic field vector is 0°, resulting in no deflection. When the particle moves perpendicular to the magnetic field lines, the magnetic force acts as a centripetal force, causing the particle to move in a circular path.
The radius of the circular path can be determined using the equation r = mv / (qB), where r is the radius, m is the mass of the particle, and q is its charge. When the particle moves at an angle to the magnetic field lines, the magnetic force acts as a combination of a centripetal force and a deflecting force, causing the particle to move in a curved path.