Answer:
Explanation:
Resistance of the tungsten wire
R = resistivity x length / cross sectional area
= 
= 107 x 10⁻⁴ ohm
Resistance at 120 degree can be obtained from the following formula
= 155.15 x 10⁻⁴ ohm
= 160 x 10⁻⁴ ohm ( rounding off to two syg fig )
current = 12.5
potential diff = 12.5 x 155.15 x 10⁻⁴ V
= 0 .1939 V
= .19 V
required electric field = potential diff / length of wire
= .1939 / 16 x 10⁻²
= 1.2 N / C
Answer:
Explanation:
power of a heating element = V² / R where V is voltage and R is resistance
putting in the values
5200 = 75² / R
R = 1.082 ohm
Formula for resistance
R = ρ L / S , ρ is resistivity , L is length and S is cross sectional area
1.082 = 5 x 10⁻⁷ x L / (3.83 x 10⁻⁶)
L = 8.29 m
b )
power of a heating element = V² / R , R is new resistance
5200 = 120² / R
R = 2.77 ohm
R = ρ L / S , ρ is resistivity , L is length and S is cross sectional area
2.77 = 5 x 10⁻⁷ x L / (3.83 x 10⁻⁶)
L = 21.22 m
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