Question 1: Define electrical resistance and explain its role in an electric circuit.

Answer: Electrical resistance is a measure of how much a material opposes the flow of electric current. It determines how much current flows for a given voltage in a circuit.

Question 2: Describe the main factors that affect the resistance of a wire.

Answer: The resistance of a wire depends on its length, cross-sectional area, material (resistivity), and temperature.

Question 1: A copper wire of length 10 meters and cross-sectional area 1 mm² has a resistivity of 1.68 x 10^-8 Ω·m. Calculate its resistance. (Use R = ρ * L / A)

Answer: 0.168 Ω

Question 2: If the resistance of a resistor is 5 Ω and the voltage across it is 20 V, what is the current flowing through it? (Use Ohm's Law: I = V / R)

Answer: 4 A

Question 3: A wire made of aluminum has a resistivity of 2.82 x 10^-8 Ω·m, length 15 meters, and cross-sectional area 2 mm². Calculate its resistance.

Answer: 0.212 Ω

Question 1: Describe an experiment to measure the resistance of a wire. What variables would you control, and what safety precautions should you take?

Answer: To measure resistance, set up a circuit with a power supply, the wire, an ammeter, and a voltmeter. Vary the current and record voltage and current to calculate resistance using Ohm's law. Control variables include wire length, temperature, and material. Safety precautions include ensuring connections are secure, avoiding short circuits, and handling equipment with dry hands.

Question 1: A resistor has a resistance of 10 Ω. When connected to a 12 V power supply, the current measured is 1.2 A. Based on this data, verify whether the resistance follows Ohm's law, and explain your reasoning.

Answer: Using Ohm's law, R = V / I = 12 V / 1.2 A = 10 Ω. Since the calculated resistance matches the given resistance, it follows Ohm's law.

Question 1: Explain how resistance is considered in designing electrical wiring for buildings to ensure safety and efficiency.

Answer: In building wiring, materials with low resistance like copper are used to reduce energy loss as heat. Wire thickness and length are designed to keep resistance low, preventing overheating and fire hazards. Proper insulation and circuit breakers are also used to manage resistance-related issues and ensure safety.