1. Two loads are connected in parallel to a 120 V source. If the 40 W lamp is left on for 3 hr/day and the 75 W lamp is left on for 5 hr/day calculate the current in each loa

Explanation:

Since both loads at connected in parallel, the voltage across them will be the same.

The voltage across parallel connected loads are the same.

Let the loads be R1 and R2

Power = IV

I is the current

V is the voltage

P= V²/R

R = V²/P

Get the first load R1

R1 = V²/P1

R1 = 120²/40

R1 = 360ohms

Get the second load R2

R2 = V²/P2

R2 = 120²/75

R2 = 192ohms

Current in R1 will be;

P1 = I1²R1

I1² = P/R1

I1² = 40/360

I1² = 1/9

I1 = √1/9

I1 = 1/3

I = 0.33A

Current in R2(second load) will be;

P2 = I2²R2

I2² = P/R2

I2² = 75/192

I2² = 0.390625

I2 = √0.390625

I2 = 0.625A

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it