Question 1: The National Grid is a network that transmits electricity from power stations to consumers across the UK. It uses high voltages to reduce energy loss during transmission. This worksheet reviews how the grid operates and its importance.

Answer: The National Grid transmits electricity using high voltages to minimise energy loss, connecting power stations to homes, businesses, and industries efficiently and safely.

Question 1: Define the term 'step-up transformer' used in the context of the National Grid.

Answer: A device that increases the voltage of electricity for efficient transmission over long distances.

Question 2: Explain why high voltages are used for transmitting electricity in the National Grid.

Answer: High voltages reduce current for the same power, decreasing energy loss as heat in the transmission cables.

Question 3: Multiple Choice: Which component in the National Grid reduces voltage before electricity reaches consumers?

Answer: Step-down transformer

Question 4: Fill in the blank: The high-voltage transmission lines are supported by tall __________ to keep them insulated and safely above the ground.

Answer: pylons

Question 5: Describe one safety feature used in the National Grid to protect workers and the public.

Answer: Insulation and safety barriers around high-voltage equipment and warning signs to prevent accidental contact.

Question 1: Calculate the power transmitted if the current in a transmission cable is 200 A and the voltage is 400 kV. Use the formula Power (P) = Voltage (V) × Current (I).

Answer: P = 400,000 V × 200 A = 80,000,000 W or 80 MW

Question 2: If the current in a transmission line is reduced from 200 A to 150 A while maintaining the same power, what is the new voltage? Show your working.

Answer: V = P ÷ I = 80,000,000 W ÷ 150 A ≈ 533,333 V or approximately 533 kV

Question 1: Identify two safety precautions that workers must follow when working on high-voltage transmission lines.

Answer: Wearing insulating gloves and using insulated tools; maintaining a safe distance from live wires.

Question 2: Describe a basic procedure for safely switching off a section of the National Grid for maintenance.

Answer: The procedure involves isolating the section using circuit breakers, confirming the absence of voltage, wearing appropriate PPE, and following safety protocols before maintenance.

Question 1: A power station generates 500 MW of electricity. If the transmission efficiency is 95%, how much electricity reaches consumers? Show your calculation.

Answer: Electricity received = 500 MW × 0.95 = 475 MW

Question 2: Explain why the voltage is stepped down near the point of use, and how this benefits consumers.

Answer: Stepping down voltage reduces the risk of electric shock and allows appliances to operate at safe, standard voltages.

Question 1: Discuss how the National Grid contributes to the integration of renewable energy sources like wind and solar power.

Answer: The grid allows for the distribution of electricity generated from renewable sources across the country, balancing supply and demand, and enabling the integration of intermittent sources like wind and solar.

Question 2: Identify one technological advancement that has improved the safety or efficiency of the National Grid and briefly explain its impact.

Answer: The development of smart grid technology improves real-time monitoring and control, increasing efficiency and enabling quicker response to faults or changes in demand.