Term 1 Revision

Kinetic Particle Model

100

Question: What are the three states of matter described by the kinetic particle model?

Answer: Solid, liquid, and gas.

200

Question: What is the difference between heat and temperature?

Answer: Heat is the transfer of thermal energy, while temperature is the measure of the average kinetic energy of particles in a substance.

300

Question: What are the three main types of heat transfer, and how do they work?

Answer:

• Conduction: Transfer of heat through direct contact of particles.
• Convection: Transfer of heat through the movement of fluids (liquids or gases).
• Radiation: Transfer of heat through electromagnetic waves without needing a medium.

400

Question: What are the SI units for temperature and heat energy, and why are they important in global science communication?

Answer: Temperature is measured in Kelvin (K) and degrees Celsius (°C); heat energy is measured in Joules (J). Standard units ensure consistency in scientific communication worldwide

500

Question: Explain the difference between internal energy and thermal energy.

Answer: Internal energy is the total kinetic and potential energy of particles in a system, while thermal energy refers only to the total kinetic energy of all particles in a system.

Temperature

100

Question: What is the formula used to convert temperature from Celsius to Kelvin?

Answer: Tk=Tc+273

200

Question: Why is the Kelvin scale referred to as an "absolute" temperature scale?

Answer: Because it starts at absolute zero (0 K), the theoretical point where all molecular motion stops

300

Question: How does absolute uncertainty differ between analog and digital measuring devices?

• Analog devices: Uncertainty is half of the smallest scale division.

• Digital devices: Uncertainty equals the smallest increment displayed.

400

Question: What happens to the kinetic energy of molecules as temperature increases, and how does this relate to the Kelvin scale?

Answer: As temperature increases, the kinetic energy of molecules increases. The Kelvin scale directly links temperature to the thermal energy of a system, where 0 K represents zero kinetic energy.

500

Question: How do you calculate percentage uncertainty, and why must temperature be converted to Kelvin before calculating it?

• Formula: Percentage Uncertainty=(Ab Unc / Measurement)×100
• Reason for conversion: Since Kelvin is an absolute scale, it provides a more accurate representation of uncertainty than Celsius.

Specific Heat

100

Question: What is the formula used to calculate the heat energy transferred to or from a substance?

Answer: Q=mcΔT

200

Question: What is specific heat capacity, and how does it affect how substances heat up or cool down?

Answer: Specific heat capacity (ccc) is the amount of energy required to raise the temperature of 1 kg of a substance by 1°C (or 1 K). Substances with higher specific heat capacity heat up and cool down more slowly, while those with lower specific heat capacity heat up and cool down more quickly.

300

Question: If two objects of different materials receive the same amount of heat energy, will their temperature increase by the same amount? Why or why not?

Answer: No, because temperature change depends on the specific heat capacity (ccc) of the material. A substance with a higher specific heat capacity will experience a smaller temperature change compared to a material with a lower specific heat capacity.

400

Question: A 2 kg block of metal absorbs 10,000 J of heat energy, increasing its temperature from 20°C to 70°C. What is the specific heat capacity of the metal?

Answer:
Using Q=mcΔTQ

The specific heat capacity of the metal is 100 J/kg°C.

500

How can an experiment be designed to determine the specific heat capacity of an unknown material?

Answer:

1. Measure the mass of the substance.
2. Heat it using a known amount of energy (Q), such as using an electric heater.
3. Measure the initial and final temperature to determine ΔT.
4. Use the formula Q=mcΔT.
5. Minimize heat loss by using thermal insulation and a lid to improve accuracy.

V, I & Energy

100

Question: What are the two types of electric charge?

Answer: Positive (carried by protons) and negative (carried by electrons).

200

Question: What must happen for an electric current to flow in a circuit?

Answer: There must be a complete closed circuit with a potential difference (voltage) to push the charge carriers.

300

Question: A circuit carries 8.0 C of charge in 4.0 seconds. Use the formula sheet to calculate the current in the circuit.

Answer: Using I=q/t    I=8.0/4.0 =2.0A.  The current is 2.0 A.

400

Question: A battery supplies 500 J of energy to a circuit where 25 C of charge flows. Use the formula sheet to determine the potential difference across the circuit.

Answer: Using V=Wq     V =500/25 = 20V The potential difference is 20V.

500

Question: A 75W electric heater runs for 5 minutes. Use the formula sheet to calculate the total energy consumed.

Answer: Using P=W/  rearrange to get W=Pxt  W=75W×(5×60)s=22,500JW

The energy consumed is 22,500 J (or 22.5 kJ).

Resistance & Power

100

Question: What is resistance, and what is its SI unit?

Answer: Resistance is the opposition to the flow of electric current, measured in ohms (Ω).

200

Question: According to Ohm’s Law, what happens to the current in a circuit if the resistance increases while voltage remains constant?

Answer: The current decreases, as resistance and current are inversely proportional.

300

Question: A 12V battery is connected to a 6Ω resistor. Use the formula sheet to calculate the current.

Answer: Using R=V/I   I=V/R hence, I = 12/6 = 2A

400

Question: A 12V battery is connected to a circuit with a resistor that is used for 5 minutes. The current in the circuit is measured to be 3A. Determine how much energy is dissipated as heat in this time. Hint: You will need to use 2 formulas.  

1. P = V*I = 12x3 = 36W

2. W = P x t = 36 x (5x60) = 10,800J

The energy dissipated as heat is 10,800 J (or 10.8 kJ).

500

• Question: A student conducts an experiment to measure the resistance of two different electrical components. The voltage and current data are recorded, and the following graphs are obtained:

  • Component A has a straight-line V-I graph passing through the origin.
  • Component B has a curved V-I graph where the slope increases at higher voltages.

• Explain what type of resistor each component represents and describe how you would determine resistance for both experimentally.

Answer:

• Component A is an Ohmic resistor because its V-I graph is a straight line, meaning resistance is constant and follows Ohm’s Law.
• Component B is a Non-Ohmic resistor, such as a filament bulb or diode, where resistance changes as voltage increases.
• To determine resistance experimentally:
  • For Component A, resistance can be calculated using the gradient of the straight-line graph: R=V/I
  • For Component B, resistance must be calculated at different points using R=V/I