Physics (AS & A Level) · May / June 2018 · Paper 11 · Question 36

A uniform resistance wire XY of length 100 cm is connected in series with a cell L. Another cell M is connected in series with resistors of resistances 5.00 Ω, 10.0 Ω and 15.0 Ω. The potential difference (p.d.) between P and Q is balanced against 12.5 cm of the resistance wire, so that the ammeter reads zero. The p.d. across the other resistors is then balanced against other lengths of the resistance wire. Which balanced lengths of resistance wire correspond to the connection points given in the table?

1. AQ and R: 12.5; Q and S: 62.5; P and R: 37.5
2. BQ and R: 25.0; Q and S: 62.5; P and R: 37.5
3. CQ and R: 25.0; Q and S: 75.0; P and R: 37.5
4. DQ and R: 25.0; Q and S: 62.5; P and R: 12.5

As printed in the paper