A physics class is investigating the combined resistance of two identical resistors arranged either in series or in parallel.
A student sets up the resistors in a parallel circuit (Circuit A) under a specific voltage. The voltage across the parallel combination is measured as Vp=3.0 VV_p = 3.0\text{ V}Vp=3.0 V and the total current from the source is Ip=0.60 AI_p = 0.60\text{ A}Ip=0.60 A.
Next, the student rearranges the same two resistors into a series circuit (Circuit B). The readings are recorded as:
State the standard SI symbols used for the units of voltage, current, and resistance.
Calculate the combined resistance of the resistors for both configurations:
Calculate the ratio yyy of the resistances using the equation:
y=RsRp y = \frac{R_s}{R_p} y=RpRsAn engineer sets up a test circuit containing two DC motors connected in parallel to a power source. An ammeter is connected to measure the total circuit current, and a variable resistor is placed in series with the power source.
State the primary purpose of the variable resistor in this control circuit.
Describe how a voltmeter should be connected to measure the potential difference across one of the motors.
136 exam-style questions on CIE IGCSE Physics 4.3 Electric circuits, covering 4.3.1a Circuit diagrams and circuit components, 4.3.2a Series circuits, 4.3.2b Parallel circuits, 4.3.2c Current and potential difference in circuits, 4.3.2d Combined resistance of resistors in parallel, and 4.3.3 Action and use of circuit components. Each one has a worked solution and a mark scheme showing where the marks go.