phyisics - c 2 : Resistance

These flashcards cover key concepts regarding electrical components, resistance, Ohm's law, and calculations related to electrical measurements.

What are the electrical units of measurement for current, potential difference, power, energy, and resistance?

Current in amperes (A), potential difference in volts (V), power in watts (W), energy in joules (J), resistance in ohms (Ω).

What does Ohm's Law state?

Ohm's Law states that the potential difference (V) across a conductor is directly proportional to the current (I) flowing through it, provided the temperature stays constant.

How is resistance calculated in an electrical circuit?

Resistance (R) is calculated using the equation R = V / I, where V is the potential difference in volts and I is the current in amps.

What is the resistance of a component that has a potential difference of 200V and a current of 80mA?

Resistance = 200V ÷ 0.08A = 2500Ω.

What happens to the resistance of a filament lamp as the temperature increases?

As the resistance increases, the temperature of the filament rises, making it harder for electrons to flow.

What is a light-dependent resistor (LDR)?

An LDR is a component that changes its resistance based on the amount of light that hits it.

What are the differences between ohmic conductors and non-ohmic conductors?

Ohmic conductors have a constant resistance regardless of voltage/current changes, while non-ohmic conductors have a variable resistance that changes with voltage/current.

How does resistance change with the length and temperature of a wire?

Resistance increases with the length of the wire since there are more collisions with metal ions, and it also increases with temperature due to more ion vibration.

What components are used to measure current and potential difference in circuits?

An ammeter measures current, and a voltmeter measures potential difference.

Why does the resistance of your body change with moisture?

Dry skin has higher resistance (about 1,000 Ω) than wet skin (about 100 Ω), making electricity more dangerous when the skin is wet.