Answer:
240 ohms
Explanation:
From Ohms law we deduce that V=IR and making R the subject of the formula then R=V/I where R is resistance, I is current and V is coltage across. Substituting 120 V for V and 0.5 A for A then
R=120/0.5=240 Ohms
Alternatively, resistance is equal to voltage squared divided by watts hence 
Answer:
292.3254055 W/m²
469.26267 V/m

Explanation:
P = Power of bulb = 90 W
d = Diameter of bulb = 7 cm
r = Radius = 
= Permittivity of free space = 
c = Speed of light = 
The intensity is given by

5% of this energy goes to the visible light so the intensity is

The visible light intensity at the surface of the bulb is 292.3254055 W/m²
Energy density of the wave is

Energy density is also given by

The amplitude of the electric field at this surface is 469.26267 V/m
Amplitude of a magnetic field is given by

The amplitude of the magnetic field at this surface is 
Answer:
28.6666666667 or 29
Explanation:
the formula for voltage (if power is involved)
V = P/i
86 ÷ 3
28.6666666667
if you want your can round to get a more simple answer
29
Answer:
Zero
Explanation:
Two long parallel wires each carry the same current I in the same direction. The magnetic field in wire 1 is given by :

Magnetic force acting in wire 2 due to 1 is given by :


Similarly, force acting in wire 1 is given by :
According to third law of motion, the force acting in wire 1 will be in opposite direction to wire 2 as :

So, the total magnetic field at the point P midway between the wires is in what direction will be zero as the the direction of forces are in opposite direction.
Answer:
When a current carrying wire is in your left hand, thumb in the direction of the magnetic field lines, your fingers point in the direction of the current
Explanation:
This is in line with the left hand rule