A - Level Physics - Electric fields - Low stakes quiz 1

Two identical positive point charges, P and Q, separated by a distance r, repel each other with a force F. If r is decreased so that the electrical potential energy of Q is doubled, what is the force of repulsion?

• 0.5 F

• F

• 2 F

• 4 F

The force between two point charges is F when they are separated by a distance r. If the separation is increased to 3r, what is the force between the charges?

A repulsive force F acts between two positive point charges separated by a distance r. What will be the force between them if each charge is doubled and the distance between them is halved?

• F

• 2 F

• 4 F

• 16 F

Two protons are 1.0 × 10^–14 m apart. Approximately how many times is the electrostatic force between them greater than the gravitational force between them? (Use the Data and Formulae booklet)

• 10²³

• 10³⁰

• 10³⁶

• 10⁴²

A continuous stream of water falls through a vertical distance of 100 m.

Assume no thermal energy is transferred to the surroundings.

The specific heat capacity of water is 4200 J kg^–1 K^–1.

What is the temperature difference of the water between the top and bottom of the waterfall?

• 0.023 K

• 0.23 K

• 2.3 K

• 4.3 K

The wheel of the London Eye has a diameter of 130 m and rotates at a steady speed, completing one rotation every 30 minutes. What is the centripetal acceleration of a person in a capsule at the rim of the wheel?

• 1.2 × 10^–4 m s^–2

• 2.5 × 10^–4 m s^–2

• 3.9 × 10^–4 m s^–2

• 7.9 × 10^–4 m s^–2

An experiment is carried out to determine the Young modulus E of steel using a vertical wire of initial length L and cross-sectional area A. Various weights are suspended from the wire. A graph of extension against weight is plotted. What does the gradient of the graph represent?

Which quantities can be written in the fundamental units kg m^–1 s^–2?

• Tensile stress and kinetic energy

• The moment of a force and kinetic energy

• Young modulus and the moment of a force

• Young modulus and tensile stress

A student carries out an experiment to determine the resistivity of a metal wire.

She determines the resistance from measurements of potential difference between the ends of the wire and the corresponding current. She measures the length of the wire with a ruler and the diameter of the wire using a micrometer. Each measurement is made with an uncertainty of 1%

Which measurement gives the largest uncertainty in the calculated value of the resistivity?

• current

• diameter

• length

• potential difference