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GCSE OCR Physics - P5
Fichas del conjunto (42)
- 1Describe a proton.☺Found in the nucleus of an atom
☺Positive charge
☺High mass (1) - 2Describe a neutron.☺Found in nucleus of an atom
☺No charge
☺High mass (1) - 3Describe an electron.☺Orbits the nucleus in shells
☺Negative charge
☺Negligible mass (1/2000) - 4Describe how static electricity is created.1. When 2 insulating materials are rubbed together, electrons are scrapped off one and dumped on the other.
2. A positive charge is left on one material (lost electrons) and a negative on the other (gained electrons.
3. Static electricity is caused by friction.
4. Which way the electrons are transferred depends on the materials involved. - 5Give two examples of electron transfer in static electricity.☺Polyethene rod: electrons move from duster to rod.
☺Acetate rod: electrons move from rod to duster. - 6Why may static electrically charged objects stick together?Opposite charges attract to each other. Examples of this sticking are crackling and clingy clothes, dust attraction, and bad hair days.
- 7What happens if the build up of static electricity is very large?It may cause sparks because of the transfer of electrons back to it's original owner. An extreme example is lightning. Objects can be earthed or insulated to prevent this.
- 8Why may a statically charged balloon stick to an uncharged wall?1. rubbed balloon has positive charge.
2. positive charges in the wall repel.
3. positive balloon and close negative charges in wall attract. - 9The _ the resistance across the components, the _ the current that flows.1. greater
2. smaller - 10What is current?The rate of flow of electric charge.
- 11How do you calculate current?
- 12What is potential difference?It indicates the energy a power supply transfers to charge in a current and measures the "push" the power supply puts on the charge. It's the work done per coulomb of charge that passes between two points in a circuit.
- 13How do you calculate potential difference?
- 14What are the units and symbols of the following: 1. Current 2. Potential difference 3. Resistance 4. Charge1. unit = ampere (A), symbol = I
2. unit = volt (V), symbol = V
3. unit = ohm (Ω), symbol = R
4. unit = coulombs (C), symbol = Q - 15Draw these circuit symbols: Open switch, Closed switch, Cell, Battery, Lamp, Fuse, Voltmeter.
- 16Draw these circuit symbols: Diode, Resistor, Variable resistor, Ammeter, Thermistor, LDR.
- 17What does an ammeter and voltmeter do?☺Ammeter: measures current of a circuit.
☺Voltmeter: measures potential difference of a circuit. - 18What does a resistor and a light dependent resistor (LDR) do?☺Resistor: slows flow of charge in a circuit.
☺LDR: depends on light intensity. Bright light = low resistance.
Low light = high resistance. - 19What does a diode and a light emitting diode (LED) do?☺Diode: regulates the potential difference in a circuit.
☺LED: emits light when a current flows through it in a forward direction. - 20Potential difference-Current (V-I) Graphs: how does the resistor affect it?The current through a resistor (at constant temp) is directly proportional to PD. the gradient of the line depends on the resistor.
- 21V-I Graphs: how does a filament lamp affect it?As the temperature of the filament increases the resistance increases, hence the curve.
- 22V-I Graphs: how does a diode affect it?Current only flows through the diode in one direction. It has very high resistance in the other.
- 23Describe the PD, Current, Resistance, Cell voltages and Cell currents in a series circuit.1.PD is shared.
2. Current is equal.
3. Resistance adds up.
4. Cv add up.
5. Cc don't add up.
- 24Describe the PD, Current, Resistance, Cell voltages and Cell currents in a parallel circuit.1.PD is equal.
2. Current is shared between branches.
3. Total resistance is lass than that of branch with smallest resistance.
4. Cv don't add up.
5. Cc add up.
- 25Ammeters are always connected in _, even in _ circuits.1. series
2. parallel - 26Voltmeters are always connected in _, even in _ circuits.1. parallel
2. series - 27Why is there a faster current in a parallel circuit than in a series circuit?Each branch provides and extra route for charge to pass around in parallel. While in series, the more components there are the more obstructions there are for the charge to pass through.
- 28What is power and how is it calculated?It's a measurement of the rate of energy transfer.
- 29What is a magnetic field?The area of force around a magnet. Field lines are directly from North to South. There is a strong force where the field lines are closer together.
- 30What happens to a current-carrying wire?When a current flows through a wire a magnetic field is created around the wire. The field is made up of concentric circles with the wire in the center. Remember the right hand thumb rule.
- 31What happens when two magnetic fields interact?They distort each other. If this happened with a wire and a magnet, the wire would experience a force as the two fields would try to correct themselves by pushing it out. The wire can be pushed in the opposite direction by switching the magnet's poles or reversing the current.
- 32Draw a sketch of a basic electric motor.
- 33How does the coil rotate?The up and down forces on opposite ends of the wire create a turning effect and the coil rotates as a result. reversing the current will cause the coil to rotate in the opposite direction. When the coil is upright the forces work against each other, so there is no rotation.
- 34How can the motor run faster?If there is a stronger current, a stronger magnet, more turns in the coil, or and iron core.
- 35What is a commutator?A copper ring split into two parts. Blocks of carbon - "brushes" - touch each part of the commutator so that it can rotate while the current flows.
- 36How does a commutator work?It improves the coil's rotation. It reverses the current every 180 degrees rotation, swapping the forces acting on the wire and the polarity of the coil's magnetic field. When the coil is upright there are no forces acting on it as there is no current going through the commutator as the brushes aren't touching it. The coils still does rotate under it's own momentum.
- 37What is electromagnetic induction?The creation of potential difference across a conductor which is experiencing a change in magnetic field.
- 38How can electromagnetic induction be done?By moving a magnet through a coil of wire, as both have a magnetic field. When the magnet cuts through the coil's magnetic field a voltage is induced because a current is produced through the wire.
- 39Name 4 factors that may affect the voltage size.1. Strength of magnet
2. Area of coil
3. Number of turns in coil
4. Speed of movement => if magnet moves faster there will be a higher peak voltage and higher frequency. - 40Draw a sketch of a transformer.
- 41What does a transformer do?It uses electromagnetic induction to change potential difference. They only work on AC and can either increase or decrease the size of an alternating voltage.
- 42How does a transformer work?A changing voltage in the primary coil causes a changing current in the primary coil, causing a changing magnetic field in the core. This induces a changing voltage across the secondary coil, causing a changing current in the secondary coil.
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- Fichas sobre GCSE OCR Physics - P5, creado por Daniella Giannitto el 10/06/2015.
- Creado por
- Daniella Giannitto
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