| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | ] | Rate of change of an object's velocity. | Forces | @dropdown | ||||||||||||||||
2 | What is static electricity? | The separation of electric charge caused by rubbing two objects together, as electrons are transferred from one to the other. The object gaining electrons becomes negatively charged, and the object losing electrons becomes positively charged. | Electricity | |||||||||||||||||
3 | What happens when charged materials are brought together? | If the materials have the same charge, they repel each other; if the materials have different charges, they attract each other. | Electricity | |||||||||||||||||
4 | What is an electric current? | The rate of flow of charge, measured in amps. | Electricity | |||||||||||||||||
5 | What happens in an electric circuit? | The wires & components have free electrons, which move because the cell has a positive terminal and a negative terminal (making a potential difference). These charges are never used up, as they flow in a continuous loop. | Electricity | |||||||||||||||||
6 | What are conductors? | Substances or objects which allow electrical currents to pass through, because they have lots of free charges. Metals are an example, because they contain free electrons, which can move with the current. | Electricity | |||||||||||||||||
7 | What are insulators? | Substances or objects which don't allow electrical currents to pass through, because there are no charges free to move. | Electricity | |||||||||||||||||
8 | How are components in circuits shown? | Using the standard symbols for the particular components. | Electricity | |||||||||||||||||
9 | What is an alternating current (H)? | a.c. changes direction (back and forth) continuously. It is used for the mains supply, because it is easier to generate and distribute, more efficient, and can be used in a transformer. | Electricity | |||||||||||||||||
10 | What is a direct current? | d.c. always flows in the same direction as the positive and negative terminals of the cell do not change | Electricity | |||||||||||||||||
11 | At what voltage is the UK mains supply? | 230 volts. | Electricity | |||||||||||||||||
12 | What is potential difference? | The work done on or by a given amount of charge between two points on a circuit (voltage), measured in volts with a voltmeter. | Electricity | |||||||||||||||||
13 | What happens in a series circuit when more batteries are added? | The voltage and current increase. | Electricity | |||||||||||||||||
14 | What happens in a parallel circuit when more batteries are added? | The potential difference and current stays the same, but the current supplied by a single cell decreases. The cells will last longer. | Electricity | |||||||||||||||||
15 | What is the effect of adding components to a circuit? | Components, such as resistors, lamps and motors, resist the flow of charge in a circuit. This increases the resistance in the circuit, and decreases the current. | Electricity | |||||||||||||||||
16 | What happens when resistors are added to series circuits? | The resistance increases, because the battery is having to push charges through more resistors. | Electricity | |||||||||||||||||
17 | What happens when resistors are added to parallel circuits (H)? | The overall resistances reduces and the current increases, because there are more paths along which the charges can flow. | Electricity | |||||||||||||||||
18 | What happens when an electric current flows through a component (H)? | The charges in the current lose energy as they collide with vibrating ions in the wire, which is transferred to the component. This causes the component to heat up, and can make a light glow, for example. | Electricity | |||||||||||||||||
19 | What is the formula for resistance? | Resistance (ohms) = Voltage (volts, V) / Current (amperes, A). | Electricity | |||||||||||||||||
20 | What is the relationship between the current through and voltage across a resistor? | No matter what direction the current is flowing in, if the resistor's resistance stays constant, the current through and voltage across it are directly proportional (as one increases, so does the other). | Electricity | |||||||||||||||||
21 | What does a voltage-current graph for a fixed resistor look like? | A straight line in a positive direction, passing through the origin. | Electricity | |||||||||||||||||
22 | What is the effect of temperature on a thermistor? | As temperature increases, the thermistor's resistance decreases, and the current flowing through it increases. | Electricity | |||||||||||||||||
23 | What happens when two or more components are connected in a series to a battery? | The current flowing through each component is the same; the total potential difference across all the components is equal to the potential difference across the battery; the potential difference is largest across the components with the greatest resistance. | Electricity | |||||||||||||||||
24 | What happens in a series circuit when the resistance in one component increases? | The current across all components will decrease. | Electricity | |||||||||||||||||
25 | What is the relationship between the work done on the charges in the circuit and on the circuit components? | The work done on each charge in the circuit by the battery is equal to that on the circuit components. A charge moving through a large resistance has more work done on it than one moving through a small resistance. | Electricity | |||||||||||||||||
26 | What happens in a parallel circuit with one component in each parallel path (H)? | The current flowing through each component is based on the resistance of the components; the component with the smallest resistance has the greatest current flowing through it; the total current running from the battery back into the battery is equal to the current flowing through each of the parallel components. | Electricity | |||||||||||||||||
27 | What happens when more components are added in series within a parallel circuit (H)? | The current flowing through each component stays the same, and the current through the battery increases. | Electricity | |||||||||||||||||
28 | What is the effect of voltage on current and through components on a parallel circuit (H)? | The same voltage level causes more current to flow through a smaller amount of resistance than a bigger one. | Electricity | |||||||||||||||||
29 | What is the relationship between the potential difference across each component in a parallel circuit and the battery (H)? | The potential difference across each component is equal to the potential difference of the battery. | Electricity | |||||||||||||||||
30 | What is electromagnetic induction? | A current being induced by a magnet. The magnet is moved into a coil of a wire, and a voltage is induced between the ends of the wire as the magnetic field is cut. Joining the two ends together makes a current, as the circuit has been completed. | Electricity | |||||||||||||||||
31 | How can the direction of an electromagnetic current be changed? | Changing the orientation of the the magnet within the coil can induce a current in the opposite direction to the current flow | Electricity | |||||||||||||||||
32 | How can electromagnetic induction be used? | In generators, which produce electricity for the mains. | Electricity | |||||||||||||||||
33 | How does a generator work? | A magnet rotates inside the coil, and the voltage induced in the coil changes in direction and size, based on the position of the poles. This produces an alternating current, as the direction of voltage and current is reversed every half turn. After a full turn, the current and voltage are both flowing in the same direction as originally. | Electricity | |||||||||||||||||
34 | How can the voltage in a generator be increased? | Increasing the speed of the rotation of the magnet; increasing the strength of the magnetic field, e.g. with an electromagnet; increasing the number of turns on the coil; giving the coil an iron core. | Electricity | |||||||||||||||||
35 | What is power? | The amount of energy transferred per second to an appliance. It is measured in watts. | Electricity | |||||||||||||||||
36 | What is the formula for power? | Power (watts, W) = Voltage (volts, V) X Current (amperes, A). | Electricity | |||||||||||||||||
37 | What is a transformer? | A device, with two wire coils (primary and secondary) wrapped around an iron core, which is used to change the voltage of an alternating current. | Electricity | |||||||||||||||||
38 | How does a transformer work (H)? | The two coils are placed close together, and the alternating current in the primary coil creates an alternating magnetic field. This, in turn, induces an alternating current in the secondary coil. | Electricity | |||||||||||||||||
39 | How is the change in voltage by a transformer determined (H)? | By the number of turns on the coils. Voltage on primary coil (Vp) / Voltage on secondary coil (Vs) = Number of turns on primary coil (Np) / Number of turns on secondary coil (Ns). | Electricity | |||||||||||||||||
40 | What is an electric motor? | A coil of wire, which rotates in between the opposite poles of a permanent magnet, when a current flows through the coil. | Electricity | |||||||||||||||||
41 | How does a current-carrying wire work with a permanent magnet? | The wire can exert a force on the magnet (or another current-carrying wire). It also experiences a force inside a magnetic field, if the field's lines of force are at right angles to the wire (the force will be at right angles to the current direction and the lines of force from the magnetic field). | Electricity | |||||||||||||||||
42 | What happens when a current flows through the coil in a magnetic field? | The current will cut the magnetic field lines in opposite directions on each side of the coil. The field lines nearest the South pole of the magnet will be cut in the same direction, and those nearest the North pole in the opposite direction. This creates a pair of opposing forces with constant directions, giving continuous rotation. | Electricity | |||||||||||||||||
43 | What is a commutator? | A rotary switch, which turns with the coil in an electric motor, but the brushes touching it remain fixed. This ensures that, as the coil rotates, the direction of current into it is fixed. | Electricity | |||||||||||||||||
44 | How can an electric motor be used? | Hard drive disks, DVD players, electric motor vehicles, washing machines, tumble dryers, microwave ovens. | Electricity | |||||||||||||||||
45 | What is a system? | The set environment within which energy is transferred | Energy | |||||||||||||||||
46 | What is the energy associated with movement? | Kinetic Energy | Energy | |||||||||||||||||
47 | What type of energy is a longitudinal wave with a speed of 330m/s in air? | Sound Energy | Energy | |||||||||||||||||
48 | What sort of energy is given off by fluorescent objects? | Light Energy | Energy | |||||||||||||||||
49 | What type of energy is stored in stretched objects | Elastic Energy | Energy | |||||||||||||||||
50 | What type of energy is found in the nuclei of atoms? | Nuclear Energy | Energy | |||||||||||||||||
51 | What type of energy is found in objects raised off the ground? | Gravitational Potential Energy | Energy | |||||||||||||||||
52 | What type of energy is given off by hot objects? | Thermal Energy | Energy | |||||||||||||||||
53 | What type of energy is carried by electrons carrying a charge? | Electrical Energy | Energy | |||||||||||||||||
54 | What type of energy is found in bonds between substances? | Chemical Energy | Energy | |||||||||||||||||
55 | What is the unit for energy? | Joules (J) | Energy | |||||||||||||||||
56 | What is mass measured in? | kg | Energy | |||||||||||||||||
57 | What is speed measured in? | m/s | Energy | |||||||||||||||||
58 | What is extension measured in? | m | Energy | |||||||||||||||||
59 | What is gravitational field strength measured in? | N/kg | Energy | |||||||||||||||||
60 | How can you calculate the specific heat capacity? | Change in thermal energy (J) = mass (kg) x specific heat capacity (J/kg°C) x temperature change (°C) | Energy | |||||||||||||||||
61 | What is specific heat capacity? | The amount of energy required to increase the temperature of 1kg of a substance by 1°C | Energy | |||||||||||||||||
62 | What is power? | The rate at which energy is transferred or the rate at which work is done | Energy | |||||||||||||||||
63 | How do you calculate power using energy transferred? | Power = Energy transferred (J) / time (s) | Energy | |||||||||||||||||
64 | How do you calculate power using work done? | Power = work done (J) / time (s) | Energy | |||||||||||||||||
65 | What is power measured in? | Watts (W) | Energy | |||||||||||||||||
66 | What is 1 Watt equal to? | 1 Joule per second | Energy | |||||||||||||||||
67 | What is the law of the conservation of energy? | Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed | Energy | |||||||||||||||||
68 | What do we call energy that is dissipated? | Waste energy | Energy | |||||||||||||||||
69 | In a closed system what will happen to the total energy? | There will be no net change in the total energy | Energy | |||||||||||||||||
70 | How can we reduce the amount of waste energy in a system? | Use lubricants or insulation to reduce energy being lost as heat in the form of friction. | Energy | |||||||||||||||||
71 | How does thermal conductivity of a material affect the rate of conduction across the material? | The higher the conductivity, the faster the rate of conduction | Energy | |||||||||||||||||
72 | How does the thickness of a wall affect the rate of cooling of a building? | The thicker the wall, and the lower its conductivity, the slower it will lose heat. | Energy | |||||||||||||||||
73 | What is air resistance? | The force exerted on an object by the air, when it moves through it. | Forces | |||||||||||||||||
74 | What is average speed? | The distance moved by an object divided by the time taken for this to happen. Scalar | Forces | |||||||||||||||||
75 | What is displacement? | The length and direction of the straight line from the initial position of an object to its position at a later time. Vector | Forces | |||||||||||||||||
76 | What is distance? | The length of the path along which an object moves. scalar. | Forces | |||||||||||||||||
77 | What is a distance-time graph? | A way of summarising the motion of an object by showing how far it has moved from its starting point at every instant during its journey. | Forces | |||||||||||||||||
78 | Define a force | Anything that changes the size, direction or speed of an object. | Forces | |||||||||||||||||
79 | Define a non contact force | A force that involves areas of effect which are not physically touching | Forces | |||||||||||||||||
80 | Define friction | A force that opposes motion between two surfaces that are in contact | Forces | |||||||||||||||||
81 | Define an interaction pair | A pair of forces that are equal in strength, but opposite in direction. | Forces | |||||||||||||||||
82 | Define instantaneous speed | The rate at which an object is moving at a given moment in time. | Forces | |||||||||||||||||
83 | Define kinetic energy | The energy that something has owing to its motion. | Forces | |||||||||||||||||
84 | Define momentum | A property of any moving object. Mass x Velocity | Forces | |||||||||||||||||
85 | Define reaction as a force | The force exerted by a hard surface on an object that presses on it. | Forces | |||||||||||||||||
86 | What is a resultant force? | The sum, taking their directions into account, of all the forces acting on an object. | Forces | |||||||||||||||||
87 | What is velocity? | Speed in a given direction. | Forces | |||||||||||||||||
88 | What is a velocity-time graph? | A graph that can be used to plot the velocity of an object versus time. | Forces | |||||||||||||||||
89 | What are contact forces? | A force that involves objects that are physically touching | Forces | |||||||||||||||||
90 | What is a scalar quantity? | Only has a magnitude | Forces | |||||||||||||||||
91 | What is a vector quantity? | Has a magnitude and a direction | Forces | |||||||||||||||||
92 | Is Acceleration a vector or scalar? | Vector because it requires a change in velocity | Forces | |||||||||||||||||
93 | What is the uniform acceleration of a falling object under gravity? | 10 m/s/s | Forces | |||||||||||||||||
94 | Define weight | The affect of gravity on mass. | Forces | |||||||||||||||||
95 | Define mass | The amount of matter in an object | Forces | |||||||||||||||||
96 | What is newtons first law? | If the resultant force is 0 - the object remains stationary or is travelling at a constant speed | Forces | |||||||||||||||||
97 | What is newtons second law? | F = ma | Forces | |||||||||||||||||
98 | What is newtons third law? | For every action there is an equal sized force in the opposite direction | Forces | |||||||||||||||||
99 | Define Inertia | the property of an object to remain in a constant state unless acted on by an external resultant force | Forces | |||||||||||||||||
100 | What is the braking distance? | The distance travelled in the process of coming to a stop | Forces |