Static electricity

A flour mill is a factory where flour is produced.

The photograph shows some flour moving through metal channels in the flour mill.

The flour particles can become charged as they move through the metal channels.

Explain how the flour particles can become charged.

The charged flour particles move away from each other as they fall from the end of each channel.

Complete the passage by writing a suitable word or words in each blank space.

Flour particles move away from each other because they have

_........ charges. This causes the flour particles

to exert_........ forces on each other.

The dust created by producing flour in a flour mill is dangerous because the dust is flammable. This creates a risk of an explosion.

Explain why connecting the metal channels to earth reduces the risk of an explosion in a flour mill.

A student uses this apparatus to investigate static electricity.

The positively charged ball is suspended vertically on a long length of string.

The ball is made of a material that is a good electrical conductor.

Name a material that is a good electrical conductor.

Explain, in terms of the movement of charged particles, how the ball has become positively charged.

The student places a centimetre scale behind the length of string.

The string lines up with the 5.0 cm mark on the scale when the ball is in its resting position, as shown in diagram 2.

The student brings a negatively charged polythene rod near to the right side of the ball.

The ball moves, as shown in diagram 3.

Explain how the movement of the ball shows that the charge on the polythene rod is negative.

In diagram 3, the string lines up with the 7.2 cm mark on the scale.

The student moves the polythene rod slightly further away from the ball.

Predict a possible reading on the scale.

The student extends the investigation by measuring the reading on the scale for rods made from different materials.

As a control variable, the student charges each rod by rubbing it with a cloth the same number of times.

Give two other control variables for the student’s investigation.

The bar chart shows the results of the student’s investigation.

Justify the use of a bar chart to present the student’s results.

Deduce what can be concluded about the charge on each of the rods used in the investigation.

Use information from the bar chart to help your answer.

The diagram shows a rod and a cloth.

When the rod is rubbed with the cloth, the cloth becomes positively charged and the rod becomes negatively charged.

Explain how the cloth has become positively charged.

The negatively charged rod makes contact with a metal object connected to the ground.

There is an ammeter in series with the object and the ground.

Explain why the ammeter shows a current for a short time and then shows no current.

State the formula linking charge transferred, current and time.

The mean current displayed on the ammeter is 6.8 × 10^–6A.

The current lasts for 3.7 ms.

Calculate the charge transferred.

This question is about electrostatics.

A polythene rod is rubbed with a cloth, which causes both the rod and the cloth to become charged.

Which of these is the force that causes the rod and the cloth to become charged?

The polythene rod becomes negatively charged.

Which of these statements explains how the rod has become negatively charged?

A student has rods made from different materials.

The student rubs each rod the same way with a cloth.

The student measures the charge gained by each rod three times.

The table shows the results.

One of the readings for the polythene rod is anomalous.

Circle the anomalous result in the results table.

State how the student should deal with the anomalous result.

Calculate the mean charge for the polythene rod.

Describe how the student could use the rods to demonstrate that there are two different types of electric charge.

The diagram shows a machine that can be used to measure the speed of fast‑moving protons.

At the start, the proton is attracted towards a negatively charged plate.

Give a reason why the proton is attracted to the negatively charged plate.

The proton accelerates at 1.90 × 10¹¹m / s² from rest to a speed of 1.38 × 10⁵m / s.

Show that the time taken for this acceleration is about 7 × 10^–7s.

The proton passes through a hole in the negatively charged plate and enters an area where there is a magnetic field.

The magnetic field exerts a force on the proton, as shown in the diagram.

This force causes the proton to follow a circular path without changing speed.

Give the direction of the magnetic field.

Suggest how increasing the strength of the magnetic field will affect the proton when it is moving in the magnetic field.

The diagram shows the inside of an oscilloscope.

Electrons leave the electron supply and accelerate towards the screen.

The stream of electrons hits the screen.

The grid is connected to the positive terminal of a high voltage power supply.

Explain, in terms of the movement of particles, how the grid has become positively charged.

State the formula linking kinetic energy, mass and speed.

Calculate the speed of an electron when it has 1.3 × 10^–15J of kinetic energy.

The mass of an electron is 9.1 × 10^–31kg.

The stream of electrons spreads out as it travels towards the screen.

Explain why the electrons in the stream move apart from each other.

The oscilloscope can cause the electrons to move in a circle.

This produces a circular pattern on the screen.

Use the scale to determine the radius of the circle.

The time taken for the electrons to complete one orbit of the circle is 24 ms.

Calculate the orbital speed of the electrons.

Use the formula

A cleaning product is applied to a car using a sponge pad.

The sponge pad is rubbed against the car to apply the cleaning product.

Some parts of the car are made of metal and other parts are made of plastic.

The metal parts of the car are earthed.

Explain why the pad becomes charged when rubbing the plastic parts, but not when rubbing the metal parts.

The sponge pad is held near a metal post that is connected to the ground.

The sponge pad discharges with a small spark through the air to the metal post.

The sponge pad stores 5.0 mJ of energy in its electrostatic store.

The voltage between the sponge pad and the metal post is 6000 V.

Calculate the charge transferred by the spark.

The small spark between the sponge pad and the metal post demonstrates that the sponge pad is charged.

Describe a different experiment that could demonstrate that the sponge pad is charged.

You may draw a diagram to support your answer.

The photograph shows a person using a roll of plastic wrapping to cover a plate of food.

The plastic wrapping sticks to the plate due to electrostatic charges.

The passage explains why the plastic wrapping sticks to the plate.

Use words from the box to complete the passage.

Each word may be used once, more than once, or not at all.

The person pulls a layer of plastic wrapping from the roll.

Forces between the layers of wrapping transfer particles called_........ from one layer to another layer.

The layer gaining these particles acquires a_........ charge.

The layer losing these particles acquires a_........ charge.

The negatively charged layer of wrapping repels_........ in the plate, leaving a positive charge in the plate where it touches the plastic wrapping.

The wrapping and plate_........ due to them having opposite charges.

A tumble dryer is a household device that dries clothes.

The clothes rotate in a heated cylinder.

Clothes often stick together when they are dry because they become electrostatically charged.

A student investigates how different materials charge electrostatically in a model tumble dryer.

The diagram shows the model tumble dryer.

This is the student’s method.

• put four dry squares of the same material into the cylinder

• rotate the cylinder at constant speed for three minutes

• remove any squares that are stuck together

• measure the force needed to pull the squares apart

• repeat this for squares of different material

Name a device the student could use to measure a force.

State the independent and dependent variables in this investigation.

State a control variable in this investigation.

Explain how the squares of material stick together.

Use ideas about electrostatic charge in your answer.

The table shows some of the student’s results.

Explain which type of graph is the most appropriate to present the results from this investigation.

State the formula linking charge, current and time.

When the squares of material are pulled apart there is a small spark.

There is a current of 4.310^–6A in the air for a time of 2.3×10^–3s.

Calculate the charge that is transferred.

The SPS is a particle accelerator in Geneva.

The SPS can accelerate sulfur particles to speeds almost as fast as the speed of light.

Neutral sulfur particles can become positively charged sulfur particles.

Describe the difference between a neutral sulfur particle and a positively charged sulfur particle.

Diagram 1 shows a section of the SPS.

Positively charged sulfur particles are introduced at point P and accelerate to the right.

Explain why the positively charged sulfur particles accelerate.

The sulfur particles enter a large tube and complete a circular orbit.

Diagram 2 shows a sulfur particle, travelling with velocity v, in the tube.

A magnetic force acts on the positively charged sulfur particle.

This force makes the particle travel in a circle.

The force is labelled F.

Use the left-hand rule to determine the direction of the applied magnetic field.

The tube has a radius of 1.1 km and the sulfur particle has an orbital speed of 2.9 × 10⁸m/s.

Calculate the orbital period of the sulfur particle.

Diagram 1 shows a machine used for demonstrating electrostatics.

When the handle is turned, the dome becomes positively charged.

In terms of electron movement, give a reason why the metal dome becomes positively charged.

When the handle is turned for 15 s the dome gains 0.50 J of energy in its electrostatic store as it becomes charged.

The voltage between the dome and the earth is 120 kV.

Calculate the mean charging current during this time.

The metal dome is discharged.

A thin metal case is then placed on top of the metal dome, as shown in Diagram 2.

When the handle is turned, the thin metal case moves upwards away from the dome.

Explain why the thin metal case starts to move upwards.

Explain why the metal case reaches a maximum height above the metal dome.

An electrostatic paint sprayer is used to paint an object.

The nozzle of the paint sprayer is positively charged.

Explain the advantage of using a charged nozzle.

The object is an electrical conductor and is initially uncharged.

Explain why the painting process would be more effective if the object were earthed.

The diagram shows part of a device used to demonstrate electrostatic charge.

Negatively charged water droplets fall into bucket A.

Describe how bucket A becomes negatively charged.

Explain why the negatively charged droplets spread out as they fall.

A droplet hits bucket A with a speed of 3.8 m/s.

Calculate the kinetic energy of the droplet when it hits bucket A.

The total charge stored in bucket A is –1.110^–10 C.

This charge passes through the air between the buckets in 9.2 × 10^–3 s, causing a spark between bucket A and bucket B.

Calculate the mean current between the buckets.

The spark transfers a charge of –1.110^–10 C.

The mean voltage between the buckets is 1.7 kV.

Calculate the energy transferred by the spark.

The ink drop experiences a horizontal electrostatic force as it falls.

Explain the direction of the electrostatic force exerted on the ink drop by the charged plates.

On the diagram, draw the path of the ink drop as it falls between the charged plates until it hits the paper.

The ink drop experiences a horizontal force of 8.510^–7N when it is between the charged plates.

The mass of the ink drop is 1.110^–10kg.

Calculate the horizontal acceleration of the ink drop when it is between the charged plates.

acceleration =_........ ²

The ink drop has no initial horizontal velocity before it passes between the charged plates.

After passing between the charged plates, the horizontal velocity of the ink drop is 3.9 m/s.

Calculate the horizontal distance travelled by the ink drop as it passes between the charged plates.

Give your answer in mm.

Explain how another ink drop could be deflected in the opposite direction by a greater distance using the charged plates in the inkjet printer.

This question is about electrostatics.

A student uses a plastic rod to investigate electrostatics.

Describe how the student could have charged the plastic rod.

The student uses a meter to measure the amount of charge on the rod.

The meter displays a reading of –5.2 mC.

Which of these is the same as –5.2 mC?

The rod is negatively charged.

Which statement correctly explains why the rod is negatively charged?

Using a meter is one method of demonstrating that the rod is charged.

Describe another method of demonstrating that the rod is charged.

Electrostatic charges can be useful but they can also be dangerous.

Give one use of electrostatic charges.

Explain why electrostatic charges can be dangerous when fuelling an aeroplane.

This question is about a demonstration to show the link between current and charge.

The diagram shows two metal plates, X and Y, with a metal ball moving between them.

The two metal plates have no charge before the power supply is connected.

When plate Y is connected to the positive terminal of the power supply, the plate becomes positively charged.

Explain how plate Y gains a positive charge.

The metal ball becomes positively charged when it touches plate Y.

The metal ball then moves away from plate Y towards plate X.

Explain why the metal ball moves away from plate Y.

Give a reason why the ball is made of metal.

When the metal ball moves away from plate Y to plate X, a charge of 5.1 × 10^-6 C is transferred.

State the formula linking charge transferred, current and time taken.

Calculate the current if the metal ball takes 0.45 seconds to travel from plate Y to plate X.

Suggest why the current increases if the voltage of the power supply is increased.

Give the name of the apparatus that can be used to measure current.

A student uses this apparatus to demonstrate the effect of electric charge.

He pours some fine powder into a funnel.

The fine powder moves through a length of plastic tubing and falls into a metal can.

The metal can rests on a metal cap.

The metal cap is connected to a thin piece of metal via a metal rod.

When the powder lands in the can, the thin piece of metal moves away from the metal rod.

Explain why the thin piece of metal moves away from the metal rod.

A coulombmeter measures electric charge.

The student connects a coulombmeter to the metal can.

When all the powder has landed in the can, the coulombmeter shows a reading of –9.410^–9 C.

Which statement is true for the metal can?

State the formula linking charge, current and time.

It takes a time of 12 s from when the powder starts landing in the metal can until all the powder has landed in the can.

Calculate the mean charging current.

A student charges a plastic rod by rubbing it with a cloth.

The rod becomes negatively charged.

Which statement explains how the rod becomes negatively charged?

Describe how the student could demonstrate that the rod is charged.

The student has several other rods made from different kinds of plastic.

Some rods can be charged positively and some can be charged negatively.

Describe an experiment to show that different rods have different types of charge.

You may draw a diagram to help your answer.

This is a question about alpha particles.

Describe the nature of an alpha particle.

The diagram shows the path of an alpha particle as it passes close to a nucleus.

Draw an arrow from point X to show the force on the alpha particle due to the nucleus.

Label this force Y.

Draw an arrow to show the force on the nucleus due to the alpha particle.

Label this force Z.

Explain how the path of the alpha particle shows whether the nucleus is positive, negative or neutral.

The alpha particle experiences a resultant force of 3.6 N and has a mass of 6.610^–27kg.

Calculate the acceleration of the alpha particle.