4.5.4. Force on a current-carrying conductor
A subsection of Physics, 0625, through 4. Electricity and magnetism
Listing 10 of 57 questions
An extremely violent nuclear reaction is taking place at the centre of the Sun. It is this reaction that enables the Sun to emit both a very large quantity of energy and an extremely large number of charged particles. Name the type of nuclear reaction taking place in the Sun. Many of the charged particles produced by the Sun are emitted from its surface at high speeds and travel out into space. Explain why these particles constitute an electric current. State the equation that relates the electric current I to the charge Q that is flowing. Define any other terms in the equation. Some of the particles emitted by the Sun travel straight towards the Earth until they enter the Earth’s magnetic field. Because they constitute a current, they experience a force and are deflected. Describe the relationship between the direction of the force and 1. the direction of the current, 2. the direction of the magnetic field. A negatively charged particle is travelling in a magnetic field. This is represented in . The direction of the magnetic field is into the page. negative particle direction of travel of particle magnetic field into page On , draw an arrow, labelled F, to show the direction of the force that acts on the particle.
0625_s15_qp_33
THEORY
2015
Paper 3, Variant 3
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A lightning conductor protects a tall building and the people in it against damage and injury caused by lightning strikes. The lightning conductor is a very long strip of copper that is attached to the side of the building. At the top of the building, the strip of copper is connected to a vertical metal pole and at the bottom of the building, it is buried in the ground. shows a thundercloud passing over the building. building ground metal pole lightning conductor – – – – – – thundercloud The bottom of the thundercloud is negatively charged. As the cloud moves closer to the building, the top of the metal pole becomes charged. State the sign of the charge at the top of the metal pole. Explain, in terms of the particles involved, how it becomes charged. 1 8 As the cloud passes over the building, a lightning strike occurs and a charge of 0.84C flows through the lightning conductor. The charge flows for 3.5 × 10–5s. Calculate the average current in the lightning conductor during this time. current = It is suggested that the current in the lightning conductor could be measured by connecting a laboratory ammeter between the pole and the copper strip. State one reason why this cannot be successful. The copper strip has a large cross-sectional area. State how increasing the cross-sectional area of the copper strip affects its resistance. [ 1 8
0625_s16_qp_43
THEORY
2016
Paper 4, Variant 3
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shows a current-carrying coil in a magnetic field. battery C coil connections to battery D B A F + – N S current The direction of the current in side AB of the coil is labelled. The force F on side AB is also labelled. On , draw • an arrow labelled X, on side CD, to show the direction of the current in this side of the coil, • an arrow labelled P, to show the direction of the force on CD. Give two ways of increasing the forces F and P on the sides of the coil. 1. 2. Name the particles that flow in the metal wire of the coil. The wire of the coil is replaced by a thinner wire. This wire is the same length and is made of the same metal. State and explain how this changes the current in the coil.
0625_s17_qp_32
THEORY
2017
Paper 3, Variant 2
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shows a vertical conductor passing through a horizontal piece of card. card conductor On , draw a cell and a switch in series with the conductor to form a complete circuit. Use the correct circuit symbols. A student sprinkles iron filings onto the card and closes the switch. There is a current in the conductor. Describe the pattern of the magnetic field seen. The student reverses the direction of the current in the conductor. State the effect, if any, on the pattern he sees. Describe an experiment to show that a force acts on a current-carrying conductor in a magnetic field. Show how to arrange the equipment. Include a diagram in your answer.
0625_s18_qp_31
THEORY
2018
Paper 3, Variant 1
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Questions Discovered
57