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Questions and Answers
What are the two basic types of electric cells?
What are the two basic types of electric cells?
State the S.I. unit for electric current?
State the S.I. unit for electric current?
The current is said to be 1 ohm if charge of 1 C passes through the wire in 1 s
What two things are typically used to measure electric current and potential difference?
What two things are typically used to measure electric current and potential difference?
Ammeter and Voltmeter
Where does conventional current flow? (Choose all that apply)
Where does conventional current flow? (Choose all that apply)
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What is the formula for electrical resistance in a circuit?
What is the formula for electrical resistance in a circuit?
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What is the most efficient and non-polluting lighting device?
What is the most efficient and non-polluting lighting device?
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A substance that allows electric current to flow easily is called a conductor.
A substance that allows electric current to flow easily is called a conductor.
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An insulator is a material which does not allow electric current to flow easily.
An insulator is a material which does not allow electric current to flow easily.
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State the function of the cell
State the function of the cell
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As the length of a wire increases, what happens to its resistance?
As the length of a wire increases, what happens to its resistance?
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As the temperature of a wire increases, what happens to its resistance?
As the temperature of a wire increases, what happens to its resistance?
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What is the primary function of a ammeter in an electric circuit?
What is the primary function of a ammeter in an electric circuit?
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What happens to the current flow in a circuit when the resistance is doubled and the voltage remains constant?
What happens to the current flow in a circuit when the resistance is doubled and the voltage remains constant?
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Which of these is NOT a strategy for efficient energy use?
Which of these is NOT a strategy for efficient energy use?
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State Ohms law
State Ohms law
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Study Notes
Current Electricity
- Direct current (DC) is a constant current flowing in one direction.
- Cells are sources of DC current, converting chemical energy to electrical energy.
- Primary cells undergo irreversible reactions and are discarded after use.
- Secondary cells (accumulators) have reversible reactions and can be recharged.
- Current is the rate of flow of charge.
- Current (I) = Charge (Q) / time (t).
- SI unit of current is the ampere (A).
- 1 A = 1 C/s.
- Electric circuits use various components.
Sources of Direct Current
- Primary cells: Simple voltaic cell, Leclanche cell, Daniel cell, dry cell
- Secondary cells: Lead (acid) accumulator, Ni-Fe (alkali) accumulator, Li-ion battery
Circuit Components
- Cells (or batteries): Provide electrical energy
- Wires: Conduct electricity
- Key (or switch): Controls the flow of current. Open circuit (key is open) prevents the flow. Closed circuit (key is closed) allows flow.
- Rheostat/variable resistance: Adjusts the current. Continuously variable resistances.
- Resistor box: Provides fixed resistances. Preset, fixed resistances.
- Ammeter: Measures current
- Voltmeter: Measures potential difference
- Galvanometer: Detects small currents, direction of current
Electric Current
- The rate of flow of charge.
- Conventionally, current flows from positive to negative.
- Electrons flow from negative to positive.
- Measured in amperes (A).
Potential Difference and Resistance
- Potential difference (V) is the work done per unit charge transferred (V = W/Q).
- Measured in volts (V).
- Resistance (R) is the opposition to current flow (R = V/I).
- Measured in ohms (Ω).
- Factors influencing resistance:
- Material: Some materials are better conductors than others.
- Length: Longer wires have higher resistance.
- Cross-sectional area: Thicker wires have lower resistance.
- Temperature: Higher temperatures generally increase resistance.
Insulators and Conductors
- Conductors: Allow current to flow easily. Good conductors have many free electrons.
- Examples: Copper, aluminum.
- Insulators: Do not allow current to flow easily. Poor conductors have few free electrons.
- Examples: Rubber, plastic, glass.
Closed and Open Circuits
- Closed circuit: A complete path for current flow.
- Open circuit: An incomplete path, preventing current flow.
Efficient Use of Energy
- Reducing energy consumption through better technology and practices like using energy-efficient appliances and improving insulation.
- Promoting the use of renewable energy resources.
- Educating the public about energy conservation.
- Use of LED lights: Low energy consumption, long life.
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Description
Test your knowledge on current electricity, covering concepts like direct current (DC), primary and secondary cells, and key components of electric circuits. This quiz will help you understand the flow of charge and the function of various circuit elements.
