A voltmeter with resistance `500 Omega` is used to measure the emf of a cell of internal resistance `4 Omega`. The percentage error in the reading of the voltmeter will be

Explanation

`V=E-ir`
`therefore` percentage error `=(DeltaE)/(E)xx100=(ir)/(E)xx100`
`=(((E)/(R+r))r)/(E)xx100=((r)/(R+r))xx100`
`=((4)/(500+4))xx100=0.8%`