When a current I is set up in a wire of radius r, the drift velocity is vd. If the same current is set up through a wire of radius 2r of same material, the drift velocity will be
A
4vd
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
vd2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
2vd
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
vd4
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
Open in App
Solution
The correct option is Dvd4 We know the relation between current and drift velocity given by, I=neAvd
where n= number of electrons per unit volume. e= charge on electron A= Area ⇒vd=IneA(1)
For wire with radius 2r, area Af=π(2r)2=4πr2=4A
Hence for wire of radius 2r drift velocity, vdfIneAf=Ine(4A)=vd4