ELECTRIC MOTORS AND ELECTROMAGNETIC INDUCTION
3 marks · NormalFigure 1 shows a long, straight wire carrying a current. The current flows vertically upwards out of the page.
Draw the magnetic field pattern around the wire.
State the rule used to determine the direction of the magnetic field lines.
Explain how the field strength would change if the current is increased.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Concentric circles around the wire, anticlockwise (looking from above) · must show At least two circles, arrowed anticlockwise
(b) Right-hand grip rule
(c) The strength of the magnetic field increases when the current increases. · must show Stronger field for bigger current
Must show: Circular magnetic field lines around the wire (with correct direction), Name of rule, Correct explanation
Common mistakes: Incorrect field line direction; Naming the wrong rule
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correct field pattern: at least two circles anticlockwise.
B1 (b) · 1 mark · Rule named as right-hand grip rule (accept right-hand thumb rule for wires).
B1 (c) · 1 mark · States magnetic field strength increases as current increases.
Worked solution
b) The right-hand grip rule is used to find the direction.
c) Increasing current increases strength of the magnetic field.