9702 · 9.1
Electric current flashcards
Revision flashcards for Cambridge 9702 Electric current (syllabus 9.1). Flip, recall, then mark a real past-paper question.
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What is the SI unit for electric charge?
Coulomb (C)
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How is electric current defined in terms of charge and time?
The rate of flow of electric charge, I = ΔQ/Δt.
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What is the numerical value of the elementary charge?
e = 1.60 × 10⁻¹⁹ C
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State the mean drift velocity equation for current.
I = Anvq
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What is the ideal characteristic of an ammeter for measuring current?
Zero internal resistance, connected in series.
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What are the primary charge carriers in metallic conductors?
Free electrons.
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What is conventional current?
The direction of flow of positive charge (positive to negative terminal).
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What is the SI unit for electric current?
Ampere (A), equivalent to C/s.
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What does 'quantized' mean in relation to electric charge?
Charge exists in discrete integer multiples of the elementary charge.
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How does increasing the number density (n) affect current?
A higher number density leads to a larger current, assuming other factors are constant.
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Why are ammeters connected in series?
To measure the total current flowing *through* that part of the circuit.
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What does the principle of conservation of charge state?
In a closed system, electric charge cannot be created or destroyed, only transferred. The total current entering a junction must equal the total current leaving it (Kirchhoff's First Law).
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What are the charge carriers in an electrolyte solution?
Positive and negative ions.
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A current of 1 Ampere is equivalent to what flow of charge?
One Coulomb of charge passing a point per second (1 A = 1 C/s).
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What are the two types of charge carriers in a semiconductor?
Electrons (negative) and holes (positive).