Current, Potential difference & Resistance

• What is the purpose of a cell or battery in a circuit?

  It provides the circuit with a source of potential difference.
• What is a switch used for in a circuit?

  To turn the circuit on (closed) or off (open).
• How does a fixed resistor function in a circuit?

  A fixed resistor limits the flow of current and has a constant resistance.
• What is the role of a variable resistor?

  A variable resistor has a slider that can change its resistance.
• What happens to the resistance of a thermistor as its temperature increases?

  The resistance of a thermistor decreases as its temperature increases.

  
• How does the resistance of a light-dependent resistor (LDR) change with light intensity?

  The resistance of an LDR decreases as light intensity increases.

  
• What is the function of a diode in a circuit?

  A diode allows current to flow in one direction only.

  
• What is a light-emitting diode (LED)?

  An LED emits light when a current passes through it.
• What is the purpose of an ammeter in a circuit?

  An ammeter is used to measure the current in a circuit.

  
• How is a voltmeter connected in a circuit?

  A voltmeter is connected in parallel with the component being measured.

  
• What is required for a current to flow in a circuit?

  A closed path or complete circuit is required for current to flow.
• What is the direction of current flow in a circuit?

  The direction of current flow is from the positive to the negative terminal of the power supply.
• Why is it important to draw circuit diagrams neatly?

  Neat diagrams ensure clarity and help avoid ambiguity in circuit symbols.
• What is the symbol for potential difference?

  The symbol for potential difference is V.

  
• What is the definition of potential difference across a component?

  It is the energy transferred per unit charge flowing from one point to another.
• How is potential difference measured?

  Potential difference is measured using a voltmeter.
• If a bulb has a voltage of 3 V, how much energy does each coulomb of charge lose?

  Each coulomb of charge loses 3 J of energy.
• What is the equation for calculating work done in moving a charge through a potential difference?

  Work done, W = VQ.

  
• What is electric current defined as?

  Electric current is the flow of electrical charge.
• What unit is electric current measured in?

  Electric current is measured in amperes (A).
• What does the size of electric current represent?

  The size of electric current represents the rate of flow of electrical charge.
• What is the unit of charge?

  The unit of charge is the Coulomb (C).
• How is one Coulomb defined in terms of current?

  One Coulomb is the quantity of charge that passes a fixed point per second when a current of 1 A is flowing.
• What is the relationship between charge, current, and time?

  Charge, Q = It.

  
• What is the direction of electron flow in a circuit?

  Electrons flow away from the negative terminal of a cell towards the positive terminal.
• What is conventional current?

  Conventional current is defined as the flow of positive charge from the positive terminal to the negative terminal.
• How should an ammeter be connected in a circuit?

  An ammeter should always be connected in series with the part of the circuit being measured.
• What happens to the current in a closed-loop circuit?

  The current is the same value at any point in a closed-loop circuit.
• What is resistance defined as?

  Resistance is defined as the opposition to current.
• How does resistance affect current in a circuit?

  The higher the resistance, the lower the current.
• What is the symbol for resistance?

  The symbol for resistance is R.
• How is one Ohm defined?

  One Ohm is defined as one volt per ampere (1 V / A).
• How can the resistance of a circuit be increased?

  The resistance of a circuit can be increased by adding resistors.
• What happens to current when resistance increases?

  Higher resistance results in lower current for a given potential difference.

  
• What is the relationship between current, resistance, and potential difference?

  The current through a component depends on both the resistance and the potential difference across it.

  
• What is the equation relating voltage, current, and resistance?

  The equation is V = IR.

  
• Calculate the potential difference through a resistor of resistance 10 Ω with a current of 0.3 A.

  The potential difference is $V =$$0.3 \times 10 =$$3 \text{ V}$.
• What are the three components calculated in a circuit?

  Current, resistance, and potential difference

  
• What equation relates voltage, current, and resistance?

  V = IR

  
• How do you calculate the potential difference through a resistor with a resistance of 10 Ω and a current of 0.3 A?

  V = 0.3 × 10 = 3 V