Assuming that the silicon diode having resistance of `20 Omega`, the current through the diode is (knee voltage 0.7 V)

Explanation

Here
2v
Knee voltage `V_(k) = 0.7 V`
Current in the circuit `I= 21 mA = 21 xx 10^(-3) A`
the knee voltage is the voltage drop across diode D in forward bias condition
and voltage drop across resistor `R, V_(R ) =v - V_(D )`
Wattage of R `= V_(R ) xx I = 1.3 xx 21 xx 10^(-3) W=` 0.0273 W
Wattage of D = `V_(D) xx I = 0.7 xx 21 xx 10^(-3) W`
`=0.0147 W`