What is the plate current in a diode valve under the space charge limited operation, when the plate potential is 60 V? In a diode valve, the plate current is 320 mA, then the plate potential is 240 V.
A. 30 mA
B. 20 mA
C. 40 mA
D. 10 mA
A. 30 mA
B. 20 mA
C. 40 mA
D. 10 mA
Correct Answer – C
Using Child Langmuir law, `lpropt(60)^(3//3)`
`320 prop(24)^(3//2)`………..(ii)
Dividing Eq. (i) by Eq. (ii), we get
`(320)/l = (4)^(3//2) rArr l=(320)/8 rArr l=40 mA`