Let original length be L. The new length is therefore 4L.
Let original cross sectional surface area of the wire be equal to πr^2.
This means original volume was L x πr^2 = Lπr^2
The volume is the same but the length is different so 4L x new surface area must be equal to Lπr^2. Let new surface area be equal to Y.
4L x Y = Lπr^2
=> Y = (πr^2 )/ 4
Using the resistivity formula,
R = pL/A. p which is resistivity is a constant so it stays the same
But this time, instead of L we have 4L and instead of πr^2 we have (πr^2)/4.
so the new resistance
= (4Lp)/ {(πr^2)/4}
= 16 (pL)/(πr^2)
= 16 (pL)/A. because πr^2 is A
since pL/A is equal to R from the formula, this is equal to
16 R.
R was 10 ohms
therefore new resistance is 16 x 10 = 160 ohms
Answer: option 4: A wire that is 2-mm thick and coiled.
Explanation:
The current in each wire is same. The magnetic field due to a current carrying wire increases if the wire is coiled with the more number of turns. A thick wire would cause low resistance to the current. Hence, a 2-mm thick wire which is coiled would produce the strongest magnetic field.
66.7 Watts
Explanation:
Let
ohms,
ohms and
ohms. Since
and
are in parallel, their combined resistance
is given by

or

The total current flowing through the circuit <em>I</em> is given

where

Therefore, the total current through the circuit is

In order to find the voltage drop across the 6-ohm resistor, we first need to find the voltage drop across the 1-ohm resistor
:

This means that voltage drop across the 6-ohm resistor
is 20 V. The power dissipated <em>P</em> by the 6-ohm resitor is given by

Answer:
The electric field will be decreased by 29%
Explanation:
The distance between point P from the distance z = 2.0 R
Inner radius = R/2
Outer raidus = R
Thus;
The electrical field due to disk is:
)
Similarly;
However; the relative difference is:
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Answer:The time required for half of the original population of radioactive atoms to decay is called the half-life. The relationship between the half-life, T1/2, and the decay constant is given by T1/2 = 0.693/λ.
Explanation: