Potential dividersEdexcel International A Level Physics: Mind map

Exam questions on Potential dividers

1. A 9.0 V supply of negligible internal resistance is connected across a 2.0 kΩ resistor in series with a 4.0 kΩ resistor. A voltmeter of very high resistance measures the output p.d. across the 4.0 kΩ resistor.
   Calculate the current in the resistors and the power dissipated in the 4.0 kΩ resistor.2 marks
2. A light-meter circuit has a 6.0 V supply of negligible internal resistance, a light-dependent resistor (LDR) and a 10 kΩ fixed resistor, all in series. The output p.d. is measured across the fixed resistor with a voltmeter of very high resistance. In bright light the LDR has a resistance of 2.0 kΩ; in dim light its resistance is 40 kΩ.
   Calculate the p.d. across the LDR in dim light.2 marks
3. A temperature-sensing circuit has an NTC thermistor in series with a 4.0 kΩ fixed resistor across a 5.0 V supply of negligible internal resistance. The output p.d. is taken across the fixed resistor. At 20 °C the resistance of the thermistor is 12 kΩ and at 60 °C it is 1.0 kΩ.
   Calculate the output p.d. of the circuit at 20 °C.3 marks