A wire of nichrome of length 80cm has a resistance of 50 ohms. if the wire is four folded, find new resistance.

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3125

To find the new resistance of the wire after it is four folded, we need to consider the change in length and the change in cross-sectional area of the wire.

First, let's consider the change in length. If the original wire has a length of 80 cm and it is four folded, the new length will be 80 cm / 4 = 20 cm.

Next, let's consider the change in cross-sectional area. When a wire is folded, its cross-sectional area increases. Since we are folding the wire four times, the cross-sectional area will increase by a factor of 4.

Now, we can use these values to calculate the new resistance. The resistance of a wire is given by the formula:

Resistance = (resistivity * length) / cross-sectional area

Since the resistivity of nichrome remains constant, we can write:

Resistance1 / Resistance2 = (length1 * cross-sectional area2) / (length2 * cross-sectional area1)

Substituting the values:

Resistance1 = 50 ohms (original resistance)
length1 = 80 cm (original length)
cross-sectional area1 = 1 (original cross-sectional area, since it is not given)
length2 = 20 cm (new length)
cross-sectional area2 = 4 (new cross-sectional area)

Using the above formula:

50 / Resistance2 = (80 * 4) / (20 * 1)

Simplifying it:

50 / Resistance2 = 160 / 20

50 / Resistance2 = 8

Cross-multiplying:

Resistance2 = 50 / 8

Resistance2 = 6.25 ohms

Therefore, the new resistance of the wire after it is four folded is 6.25 ohms.

not sure what "four folded" means.

If you mean the cross-section area is multiplied by 4, then the resistance is divided by 4.

If the diameter is multiplied by 4, then the resistance is divided by 16

If the length is multiplied by 4, then also the resistance.