AQA PiXL A-Level Physics - Fields

A capacitor stores 100 mC of charge for every 0.33 kV of potential difference across its

plates. What is its capacitance?

• 0.30 mF

• 300 mF

• 3300 F

• 3.3 F

The acceleration of a bare helium nucleus in a uniform electric field of 0.6 V/mm would be:

• 1.15 x 10^-10 m/s²

• 5.75 x 10¹⁰ m/s²

• 1.15 x 10¹¹ m/s²

• 2.9 x 10¹⁰ m/s²

What is the electrostatic potential energy possessed by an electron 1.00 x 10-10 m from a proton in eV?

• -12.7 eV

• -3.70 x 10^-37 eV

• -14.4 eV

• -11.4 eV

Determine the approximate maximum EMF generated by an a.c. generator if the magnetic flux through its 20 turn coil is as shown in the flux-time graph shown.

• 1200 V

• 120 V

• 60 V

• 6000 V

A -12 μC is located at x = 0 cm and a 3 μC charge at x = 4 cm. What is the strength of the electric field at location x = 6 cm, defining the positive x axis as positive?

• +2.95 x 10⁵ N/C

• 0

• +3.75 x 10⁷ N/C

• -2.95 x 10⁷ N/C

Determine the maximum weight a 20.0 m length of wire could possess in order for it to float in the Earth’s magnetic field per amp of current through it. Assume the Earth’s field is uniform and perfectly horizontal with a magnitude of 50.0 μT.

• 1.0 N/A

• 1.0 mN/A

• 0.1 mN/A

• 100 mN/A

Three identical capacitors are placed in series. When discharged through a 33 kΩ resistor they lose 95% of their charge in 90 ms. What value is each capacitance?

• 0.30 μF

• 2360 nF

• 0.024 mF

• 2.73 x 10^-6 F

The two wires in the diagram have the currents indicated, both in the same direction, into the page. In the absence of any external magnetic fields they experience a force…

• of repulsion from each other, the forces being equal and opposite

• of attraction towards one another, the forces being equal and opposite

• of repulsion from each other, the force on the 1 A wire being twice that of the 2 A wire

• of attraction towards one other, the force on the 2 A wire being twice that of the 2 A wire

A simple circuit of a 12 V battery and 4 capacitors in parallel is made. The capacitors are identical in electrode area and material but the distance between their electrodes is different – this is shown in the data table.

If capacitor C₁ has a capacitance of 3600 nF, how much energy is stored by the capacitance combination in the circuit?

• 0.54 mJ

• 540 nJ

• 450 μJ

• 0.045 mJ

A graph of ln (potential difference across capacitor) on the y-axis against time on the x-axis for the discharging curve of a capacitor, resistor with resistance R and a power supply of voltage V₀ as shown would provide you with:

• a gradient of 1/RC and an intercept of V₀

• a gradient of -1/RC and an intercept of V₀

• a gradient of -RC and an intercept of ln V₀

• a gradient of -1/RC and an intercept of ln V₀