For a common-emitter transistor amplifier, the current gain is 60. If the emitter current is 6.6 mA then its base current is

Explanation

`beta=50,I_(e)=6.6mA becausebeta=(I_(c))/(I_(b)):. I_(c)=betaI_(e)=50 I_(b)`...(i)
`I_(e)=I_(c)+I_(b)` using equation (i) we get `6.6 = 50 I_(c)+I_(b) = 51 I_(b) = (6.6)/(51)=0.129 mA`
Hence `I_(c)=50 xx(6.6)/(51)=6.47mA and alpha=(beta)/(1+beta)=(50)/(51)=0.98`