How do you calculate resistance (R) given resistivity (ฯ), length (L), and cross-sectional area (A)?
Use the formula: $$R = \rho \frac{L}{A}$$
How do you calculate electric power (P) using current (I) and voltage (V)?
Use the formula: $$P = IV$$. You can also use $$P = I^2R = \frac{V^2}{R}$$ if resistance is known.
Describe the steps to find the equivalent resistance of resistors in series.
Add the individual resistances: $$R_{eq} = R_1 + R_2 + R_3 + ...$$
Describe the steps to find the equivalent resistance of resistors in parallel.
1. Find the reciprocal of each resistance. 2. Add the reciprocals. 3. Take the reciprocal of the sum: $$\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3} + ...$$
What is Ohm's Law and how can it be applied?
Ohm's Law relates voltage, current, and resistance: $$V = IR$$. It can be rearranged to find any of the three variables if the other two are known: $$I = \frac{V}{R}$$ or $$R = \frac{V}{I}$$
What are the key differences between series and parallel circuits?
Series: Single path for current, components in a line. Parallel: Multiple paths for current, current divides between paths.
Differentiate between Ohmic and Non-Ohmic devices based on their V-I characteristics.
Ohmic: Constant resistance, linear V-I graph. Non-Ohmic: Resistance changes with voltage/current, non-linear V-I graph.
Compare the internal resistance and connection method of voltmeters and ammeters.
Voltmeter: High internal resistance, connected in parallel. Ammeter: Low internal resistance, connected in series.
Compare conventional current and electron flow.
Conventional Current: Direction of positive charge flow. Electron Flow: Actual direction of electron movement (opposite to conventional current).
Compare resistance and resistivity.
Resistance: Opposition to current flow in a specific object. Resistivity: Intrinsic property of a material to resist current flow.
What is the effect of increasing the length of a wire on its resistance?
Increasing the length increases the resistance.
What is the effect of increasing the cross-sectional area of a wire on its resistance?
Increasing the cross-sectional area decreases the resistance.
What happens to the current in a circuit if the voltage is doubled, assuming resistance remains constant?
The current doubles (Ohm's Law: V=IR).
What happens to the total resistance when resistors are added in series?
The total resistance increases.
What happens to the total resistance when resistors are added in parallel?
The total resistance decreases.
What is the effect of increasing temperature on the resistivity of most materials?
Increasing temperature typically increases resistivity.
