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Electricity Flashcards

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1
Q

What is electricity?

A

The flow of electric charge

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2
Q

What are conductors and insulators?

A

Conductors allow electricity to flow; insulators block it.

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3
Q

What is voltage?

A

The force that pushes electric charge

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4
Q

What is current?

A

The flow of electric charge in a circuit.

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5
Q

What is resistance?

A

The opposition to the flow of electricity

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6
Q

What is Ohm’s law?

A

Voltage = Current x Resistance

V = IR

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7
Q

What are series and parallel circuits?

A

Series circuits have one path; parallel circuits have multiple paths.

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8
Q

What is a circuit?

A

A path for electric current.

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9
Q

What is alternating circuits? (AC)

A

Current that changes direction

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10
Q

What is direct current? (DC)

A

Current that flows in one direction

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11
Q

What is a capacitor?

A

A device that stores electrical energy.

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12
Q

What is a fuse?

A

A safety device that prevents circuit overloads.

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13
Q

What is a transformer?

A

A device that changes voltage levels.

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14
Q

What are renewable sources of energy?

A

Solar, wind, and hydroelectric power.

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15
Q

What is the purpose of a battery?

A

To store and provide electrical energy

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16
Q

What is an electromagnet?

A

A magnet created by an electric current.

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17
Q

What causes static electricity?

A

The buildup of electric charge on a surface.

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18
Q

How does electricity travel in power lines?

A

As high-voltage alternating current.

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19
Q

What is an electrical motor?

A

A device that converts electricity into motion.

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20
Q

What is an electric generator?

A

A device that converts motion into electricity.

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21
Q

Ohm’s law application: A circuit has a voltage of 12V and a resistance of 4Ω. What is the current flowing through the circuit?

A

Formula: V = IR
Given: V = 12V, R = 4 Ω
Solution: I = V/R = 12V/4 Ω = 3A

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22
Q

Power Calculation: If a toaster operates at 230V and draws a current of 3A, how much power does it consume?

A

Formula: P = VI (Power Equation)
Given: 230V, I = 3A
Solution: P = 230V x 3A = 690W

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23
Q

Energy Usage: A 60W light bulb is used for 5 hours a day. How much energy does it consume in one week?

A

Formula: E = P x t (Energy equation)
Given: P = 60W, t = 5 hours/days, 7 days
Solution: E = 60W x (5x7)
E = 60W x 35h = 2100Wh or 2.1kWh

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24
Q

Resistor Combination: You have two resistors of 6Ω and 3Ω in parallel. What is the total resistance?

A

Formula: 1/Rtotal = 1/R1 + 1/R2
Given: R1 = 6 Ω, R2 = 3 Ω
Solution: 1/Rtotal = 1/6 + 1/3
1/Rtotal = 1/6 + 2/6 = 3/6
Rtotal = 6/3 = 2 Ω

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25
Capacitor Changing: A capacitor with a capacitance of 5μF is charged with a voltage of 10V. What is the charge stored in the capacitor?
Formula: Q = CV (Charge equation) Given: C = 5μF = 5 x 10-6 F, V = 10V Solution = Q = 50 x 10-6 = 50μC
26
Ohm’s Law Application Q: If a circuit has a resistance of 8Ω and the voltage applied is 24V. What is the current flowing through it?
3A
27
Power Dissipation: A resistor has 5A of current passing through it and a voltage drop of 20V How much power does it dissipate?
100W
28
Energy Consumption: A 100W fan runs for 3 hours every day. How much energy does it consume in a week?
100W×(3×7)=100W x 21h = 2100Wh = 2.1kWh
29
Parallel Resistence Calculation: If two resistors of 10 Ω and 20Ω are connected in parallel, what is the equivalent resistance?
6.67 Ω
30
A battery supplies 500J of energy, but only 450J is used efficiently in a circuit. What is the effeciency of the system?
90V
31
What is the electric field strength near a charge of 5 x 10-6C at a distance of 2M
A = 11,250N/C
32
A wire with a resistance of 4Ω has a length of 2m. If its cross-sectional area is doubled, how will its resistance change?
New resistance is 2Ω
33
If three resistors in a circuit drop voltages of 3V, 6V, and 4V, what is the total supplied voltage?
13V
34
If an inductor of 0.5H carries a current of 4A, how much energy is stored in its magnetic field?
E = 1/2 x 0.5 x (4 squared) E = 0.25 x 16 = 4J
35
What is the purpose of a fuse in an electrical circuit?
A fuse protects a circuit by breaking the electrical connection if the current exceeds a safe level, preventing overheating and damage.
36
Which material is commonly used as an insulator in electrical wiring?
Plastic is used as an insulator because it does not conduct electricity and prevents accidental shocks.
37
What is the main function of a transformer in an electrical circuit?
A transformer changes the voltage of an electrical supply, either increasing (step-up) or decreasing (step-down) it.
38
What is the role of a circuit breaker in an electrical system?
A circuit breaker interrupts the flow of excessive current to prevent electrical fires and protect the circuit.
39
What is a renewable source of energy used to generate electricity?
Wind is a renewable energy source, unlike fossil fuels like coal, natural gas, and petroleum.
40
What is the primary purpose of grounding in electrical systems?
Grounding provides a safe path for excess electrical current to flow into the earth, preventing electrical shocks and protecting equipment.
41
What is electromagnetic induction?
Electromagnetic induction is the generation of an electric current in a conductor due to a changing magnetic field, as described by Faraday’s Law.
42
What is the function of a capacitor in an electrical circuit?
A capacitor stores electrical energy in the form of an electric field and can release it when needed.
43
Which type of current is used in household electrical systems?
Alternating current (AC) is used in households because it is more efficient for transmitting electricity over long distances.
44
What is the purpose of an electric motor?
An electric motor converts electrical energy into mechanical energy, enabling devices like fans and washing machines to function.
45
What happens to current in series circuits?
The current stays the same throughout the circuit. That means every component gets the same amount of current.
46
What is the equation that links voltage, current and resistance.
V = IR
47
How do you calculate the total resistance in a series circuit?
In a series circuit, total resistance is the sum of all individual resistances: Rtotal = R1 + R2 + R3 + Each resistor adds to the total, increasing overall resistance.
48
What is the potential difference and current graph for a filament lamp?
The potential difference vs. current graph for a filament lamp curves because increasing temperature raises resistance, limiting current growth.
49
How do LDRs affect resistance and current in a circuit?
An LDR’s resistance drops in bright light, letting more current flow. In darkness, resistance rises, limiting current. That’s why LDRs are used in automatic lighting systems.
50
What is the function of step up transformers?
Step-up transformers increase voltage while reducing current.
51
What are step up transformers used for?
They’re used in power transmission to minimize energy loss over long distances.
52
What is the function of step down transformers?
Step-down transformers decrease voltage while increasing current.
53
What are step down transformers used for?
They’re used to safely deliver electricity to homes and devices.
54
What happens to voltage in series circuits?
The voltage is split across components. The total voltage of the power supply is shared among resistors, bulbs, or other loads.
55
What happens to current in parallel circuits?
The current splits between branches. The total current from the power source is divided among the parallel paths.
56
What happens to voltage in parallel circuits?
The voltage stays the same across each branch. Every parallel component receives the full voltage from the power source.
57
What is the purpose of an earth wire in a circuit?
The earth wire provides a safe path for excess current to flow into the ground, preventing electric shocks.
58
How does a circuit breaker differ from a fuse?
A circuit breaker can be reset after tripping, while a fuse must be replaced once it blows.
59
Why are high voltages used in power transmission?
High voltages reduce energy loss during transmission by minimizing current flow.
60
What is the function of a diode in a circuit?
A diode allows current to flow in one direction only, preventing reverse flow.
61
How does the resistance of a filament lamp change as the temperature of the filament changes?
As the temperature of the filament increases, its resistance also increases due to more frequent collisions between electrons and atoms.
62
What is the principle of electromagnetic induction?
Electromagnetic induction occurs when a changing magnetic field induces a voltage in a conductor.
63
Why are parallel circuits often used in household wiring?
Parallel circuits ensure that each device operates independently, maintaining consistent voltage across all components.
64
How does a fuse rating affect its function in a circuit?
The fuse rating determines the maximum current it can handle before blowing. If it's too low, the fuse may blow too easily; if it's too high, it won’t effectively protect the circuit.

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