0.143 A
Explanation:
The total resistance of the circuit is

so the total current is
Itotal= V/R = 9V/35.89 ohms
= 0.25 A
To find the voltage drop across the 30-ohns resistor, use
V = Itotal × (combined resistance of 40 30)
= 0.25 A × 17.14 ohms = 4.285 volts
so the current through the 30-ohm resistor is
I = (voltage drop)/30-ohms
= (4.285 V)/(30 ohms)
= 0.143 A
Actually a black board has all colours in light or white light . So when light falls on it board absorbs all colours because all are present so no light is reflected back. That is the case, and so it will appear black as it absorbs all colours of light that fall on it .
Given forceF
1
=5N and F
2
=7N and θ=60
We know resultant force F=
5
2
+7
2
+2(5)(7)cos60
F=
25+49+35
F=
109
it's your answer