A common emitted amplifier circuit, built using an npn transistor, is shown in the figure. Its dc current gain is `250,R_(C)=1Komega` and `V_(C C)=10V`. What is the minimum base current for `V_(CE)` to reach saturation?

Options

A. 7 `muA`
B. 40 `muA`
C. 10 `muA`
D. 100 `muA`

Explanation

Current flowing in the circuit is as shown in diagram (given `beta_(b) = 250`)

When saturation state is schieved then potential difference across collector and emitter `(V_(CE)`
become zero .Hence collector current becomes.
`i_(c ) = (10)/(1000) =10 mA`
DC current gain can be written as follows
`beta= (i_(c ))/( I_(b)) rArr 250 = (10 mA)/( I_(b)) rArr (i_(B)) = 40 muA`
Hence option (b) is currect.