13033717
Description
| Question | Answer |
| What does this circuit symbol represent? | A cell |
| What does this circuit symbol represent? | A battery |
| What does this circuit symbol represent? | A lamp |
| What does this circuit symbol represent? | A voltmeter |
| What does this circuit symbol represent? | A resistor |
|
What does this circuit symbol represent?
Image:
Fuse 2 (binary/octet-stream)
|
A fuse |
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What does this circuit symbol represent?
Image:
Ldr (binary/octet-stream)
|
A light dependent resistor ( LDR ) |
| What is electric current ( I )? | Current ( I ) is the flow of negatively charged electrons. Current is described as a measure of the charge that flows past a point every second. ( As a comparison, think of measuring the amount of water flowing through a pipe. ) |
| How do we measure current ( I )? | Current ( I ) is measured in Amperes ( A ). It is measured using an Ammeter connected in SERIES. |
| What is voltage ( V )? | Voltage ( V ) is a measure of the force, or electrical energy, pushing electrons around a circuit. |
| How do we measure voltage ( V )? | Voltage ( V ) is measured in Volts ( V ). It is measured using a Voltmeter connected in PARALLEL. |
| What is resistance ( R )? | Resistance ( R ) is a measure of how difficult it is for current to flow through a wire or device. More resistance means less current because it is more difficult for it to flow. |
| How do we measure resistance ( R )? | Resistance ( R ) is measured in Ohms ( Ω ). |
| What will happen if Lamp 1 breaks? | In a SERIES CIRCUIT there is only path for the current to follow. Therefore, if L:amp 1 breaks then Lamp 2 will not work / go off. |
| What will happen if Lamp 1 breaks? | In a PARALLEL CIRCUIT there is more than one path for the current to follow. Therefore, if Lamp1 breaks then Lamp 2 will continue to work. |
| The current leaving the cell is 4A. What would the current be at: - A1 - A2 - A3 | In a SERIES CIRCUIT the value of the current is the same at all points as there is only one path for the current to follow. ( A1 = A2 = A3) |
| What would the voltmeter readings be at: - V2 - V3 | V2 = 6V and V3 = 6V In a SERIES CIRCUIT the voltage across each component will add up to the total voltage across the supply / battery. (12V = V2 + V3) or (12 = 6 + 6). |
| What would the current be at: - A1 - A2 - A3 | In a PARALLEL CIRCUIT the value of the current in the branches adds up to the total current flowing. However, more current will 'choose' to follow the easiest route around the circuit ie: the branch with a single lamp. Therefore: A1 = 6A, A2 = 4A and A3 = 2A |
| What would the voltmeter readings be at: - V1 - V2 - V3 | In a PARALLEL CIRCUIT the voltage is the same across each 'branch' or 'strand.' Therefore: V1 = 10V V2 = 5V V3 = 5V |
| a = 3.6 A therefore g = 3.6A b = 2.0 A = therefore c = 1.6 A & f = 1.6 A d = 1.2 A therefore e = 0.4 A | |
| What does this circuit symbol represent? | A variable resistor. |
| A variable resistor is a resistor for which it is possible to alter the resistance. Variable resistors can be put into a circuit to control the current and the voltage. Suggest 2 household uses for variable resistors? | Variable resistors can be used in: - Dimmer switches - Volume control |
| Calculate the voltage across a 15 Ω fixed resistor, carrying a current of 1.8 A. | V = I x R V = 1.8 x 15 V = 27 V |
| Calculate the current through a 2 kΩ resistor when there is a voltage of 230 V across it. | 2 kΩ = 2,000 Ω I = V ÷ R I = 230 ÷ 2,000 I = 0.115 A |
| An electric fire with a current of 4 A flowing through it has a voltage of 230 V across it. Calculate the resistance of the wire in the electric fire. | R = V ÷ I R - 230 ÷ 4 R = 57.5 Ω |
| Describe and explain the voltage-current graph for a fixed resistor. | The graph shows that: - If voltage is doubled then the current also doubles. - The relationship between the current and voltage is directly proportional. - The constant gradient of the graph means that the resistance remains constant and that the resistor obeys Ohm’s law. |
| Describe and explain the voltage-current graph for a filament lamp. | Up to 2V current and voltage increase at the same rate because the resistance is constant (constant gradient). From 2V to 12V the current increases at a slower rate than the voltage. The gradient is not constant so the resistance is no longer constant, therefore the filament lamp does NOT obey Ohm’s law. |
| This is a voltage-current graph for what type of component? | A fixed resistor. |
| This is a voltage-current graph for what type of component? | A filament lamp. |
| This is a voltage-current graph for what type of component? | A diode. |
| If the total resistance of the circuit below is 12 Ω , calculate the resistance of R2. | RT = R1 + R2 + R3 So: 12 = 2 + R2 + 4 So: R2 = 12 - 4 - 2 R2 = 6 Ω |
| What does electrical power mean? | Power is the rate (per second) of energy transfer ie: the amount of energy a device can transfer from one form to another per second. Power ( W) = Energy ( J ) + time ( s ) P = E + t Power is measured in WATTs ( W ) where 1 Watt is 1 Joule of energy transferred in 1 second. |
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