Potential dividersAQA A-Level Physics: Mind map

Exam questions on Potential dividers

1. A potential divider consists of a 6.0 kΩ resistor in series with a 3.0 kΩ resistor connected across a 9.0 V supply of negligible internal resistance. The output is taken across the 3.0 kΩ resistor.
   Explain why connecting the load across the output reduces the output pd.2 marks
2. A light-dependent resistor (LDR) is connected in series with a fixed 2.2 kΩ resistor across a 5.0 V supply of negligible internal resistance, forming a potential divider that controls a street lamp. The output is taken across the fixed resistor. The resistance of the LDR is 500 Ω in bright light and 20 kΩ in darkness.
   Calculate the output pd in darkness.2 marks
3. A designer needs to supply a motor with a variable pd from 0 V to 12 V from a 12 V supply of negligible internal resistance. A variable resistor with a track of total resistance 100 Ω and a sliding contact is available.
   Describe how the variable resistor should be connected so that it acts as a potential divider supplying a pd that can be varied from 0 V to 12 V.3 marks