IB Physics B.5 Current and Circuits Questionbank

A metal wire obeys Ohm's law at room temperature. As current increases, its temperature rises and its resistance increases. Which of the following best describes the shape of its $V$-$I$ graph?

In an experiment, a student determines the resistance of a wire by plotting a $V$ vs $I$ graph. Which of the following describes the resistance?

Which expression correctly gives the electrical power dissipated in a resistor?

It decreases due to increased drift speed.

It remains constant as it is an ohmic component.

It increases due to rising temperature.

It decreases because current increases.

(a) State Ohm’s law.

(b) The current in the circuit is $1.5\ \text{A}$ when the resistance is adjusted to a certain value. Calculate this resistance.

(c) The student increases the resistance. Describe and explain what happens to the current and the power dissipated in the resistor.

A straight line through the origin

A curve concave downwards

A curve concave upwards

A straight line through the origin with increasing gradient (piecewise linear)

It is equal to the area under the graph.

It is equal to the inverse of the gradient.

It is equal to the gradient of the graph.

It is constant only if the graph is curved.

$P = IV$

$P = IR^2$

$P = \frac{V}{I}$

$P = \frac{V^2}{IR}$