Question

A copper tube with mass 100 g and 10.0 cm long passes a current of 1.00 A directed to the right. A magnetic field is turned on going forward ("into the board") with a strength of 1.00 T. In grams, rounded to the nearest tenth, what will the scale read?

Answer 1

Explanation:

The given data is as follows.

Mass of copper tube, M = 100 g = 0.100 kg   (as 1 kg = 1000 g)

Length of copper tube, L = 10.0 cm = 0.100 m   (as 1 m = 100 cm)  

Current through the copper tube, I = 1.00 A

Gravitational force on copper tube, Mg = $0.1 \times 9.81$ = 0.981 N

Magnetic force on the copper tube, ILB = $1.00 \times 0.100 \times 1.00$ = 0.100 N

Force used to balance the tube, Mg- ILB = (0.981 - 0.100) = 0.881 N

Now, we will calculate the reading on scale as follows.

         Reading on scale = $\frac{0.881}{9.81}$

                                       = 0.0898 kg

Reading on scale in grams will be as follows.

              1 g = 1000 g

so,      $0.0898 kg \times \frac{1000 g}{1 kg}$        

                    = 89.8 g

Therefore, we can conclude that reading on the scale is 89.8 grams.