Ohm's Law

The ______ is the rate at which charge flows through a surface.

Answer: Current

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Explanation: Current (I) is defined as the rate of charge (Q) flow over time (t).

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Electric current Formula

Answer: I=ΔQ / Δt

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• I: Current (Amperes, A, scalar)

• ΔQ: Change in charge (Coulombs, C, scalar)

• Δt: Change in time (seconds, s, scalar).

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Example: A current of 2A means 2 Coulombs of charge pass through a wire every second.

The SI unit for current is the ______ or the Ampere

Answer: Ampere (A) = Coulumb / seconds

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Example: A smartphone charger might deliver a current of 1.5A.

The phrases "flow of current" and "current flow" are commonly used, but the word "flow" is ______ because current is already defined as a flow of charge

Answer: Redundant

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Explanation: Saying "current flow" is redundant because "current" inherently means charge flow.
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Example: Saying "water flow flow" is incorrect; similarly, "current flow" is redundant.

The word ______ means a closed loop of some sort around which current circulates.

Answer: Circuit
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Explanation: A circuit is a closed path allowing continuous charge movement.
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Example: A battery connected to a bulb with wires forms a circuit.

No charge would flow without a closed conducting path from the positive terminal of the battery into one side of the bulb, out the other side, and back to the negative terminal of the battery.

Explanation: Current requires a closed loop from the battery’s positive to negative terminal.
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Example: If a wire breaks, the circuit opens, and the bulb turns off.

The most important quantities that characterize how the bulb works in different situations are the current in the bulb and the ______ across the bulb.

Answer: Potential difference (VV)
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Explanation: Potential difference (voltage) determines the energy supplied per charge.
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Equation: V=IRV=IR, where VV = voltage (Volts, V, scalar).

A digital ______ can be used to measure voltage, current, or resistance.

Answer: Multimeter
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Example: A digital multimeter can measure a 9V battery’s voltage or a resistor’s resistance.

Ohm’s Law is given by the equation:

Answer: V = IR

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Variables:

• V: Voltage (Volts, V, scalar)

• I: Current (Amperes, A, scalar)

• R: Resistance (Ohms, Ω, scalar).

Example: If V=12VV=12V and R=4ΩR=4Ω, the current I=3AI=3A.

Materials that obey Ohm’s law and have a consistent resistance over a wide range of voltages are said to be ______.

Answer: Ohmic
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Explanation: Ohmic materials (e.g., resistors) maintain constant resistance regardless of voltage.
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Example: A copper wire behaves ohmically at low voltages.