IB Electric fields

Two copper wires X and Y are connected in series. The diameter of Y is double that of X. The drift speed in X is v. What is the drift speed in Y?

• v/4

• v/2

• 2v

• 4v

Two point charges Q1 and Q2 are one metre apart. The graph shows the variation of electric potential V with distance x from Q1. What is Q1/Q2

• 1/16

• 1/4

• 4

• 16

An electron enters the region between two charged parallel plates initially moving parallel to the plates.

The electromagnetic force acting on the electron

• causes the electron to decrease its horizontal speed

• causes the electron to increase its horizontal speed

• is parallel to the field lines and in the opposite direction to them

• is perpendicular to the field direction

An ion of charge +Q moves vertically upwards through a small distance s in a uniform vertical electric field. The electric field has a strength E and its direction is shown in the diagram.

What is the electric potential difference between the initial and final position of the ion?

•  $\frac{EQ}{s}$  

• EQs

• Es

• E/s

An electron is accelerated through a potential difference of 2.5 MV. What is the change in kinetic energy of the electron?

• $0.4\ \mu J$

• 0.4 nJ

• 0.4 pJ

• 0.4 fJ

The diagram shows two equal and opposite charges that are fixed in place.

At which points is the net electric field directed to the right?

• X and Y only

• Z and Y only

• X and Z only

• X, Y and Z

Positive charge is uniformly distributed on a semi-circular plastic rod. What is the direction of the electric field strength at point S?

• A

• B

• C

• D

What is the definition of electric current?

• The ratio of potential difference across a component to the resistance of the component

• The power delivered by a battery per unit potential difference

• The rate of flow of electric charge

• The energy per unit charge dissipated in a power supply

Which diagram represents the pattern of electric field lines of two small positive point charges held at the positions shown?

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• 
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Coulomb’s law refers to electric charges that are

• on any charged objects

• charged hollow spheres

• charged solid spheres

• point charges