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Basic Circuit Concepts
Quick questions on Current, voltage and resistance explained: O-Level Electronics Basic Circuit Concepts
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is current is the rate of flow of charge?Show answer
Electric current is the rate at which electric charge flows past a point in a circuit:
What is conventional current?Show answer
By long-standing convention, current is drawn flowing from the positive terminal of the supply, round the external circuit, to the negative terminal. This conventional current is opposite to the direction the electrons actually drift, but every circuit rule in the syllabus is stated in terms of conventional current, so you always work with it.
What is voltage is energy per unit charge?Show answer
Potential difference, usually called voltage, across a component is the electrical energy transferred per unit charge as charge passes through it:
What is resistance is opposition to current?Show answer
Resistance is the opposition a component offers to the flow of charge. The unit is the ohm (). For a given voltage, a larger resistance allows less current. Resistance arises because moving charges collide with the atoms of the material, transferring energy to them as heat.
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