Answer:
V = I * R
R = 2 / 3.5 = .571 ohms maximum resistance of wire
R = ρ L / A where R is proportional to L and inversely proportional to A
A = ρ L / R minimum area of wire
ρ = 1 / μ = 1.67E-8 ohm-m resistivity inverse of conductivity
A = 1.67E-8 ohm-m * 225 m / .571 ohm = 6.68E-6 m^2
A = 6.68 mm^2 since 1 mm^2 = 10-6 m^2 or 1 mm = 10-3 m
A = Π r^2 = 6.68 mm^2
r = (6.68 / 3.14)^1/2 mm = 2.13 mm radius of wire
d = 2 * r = 4.26 mm
GEL IT IS COMBINATION OF SOLID AND LIQUID
Answer:
(1) 1×10⁻⁴
Explanation:
From the question,
α = (ΔL/L)/(ΔT)............. Equation 1
Where α = linear expansivity of the metal plate, ΔL/L = Fractional change in Length, ΔT = Rise in temperature.
Given: ΔL/L = 1×10⁻⁴, ΔT = 10°C
Substitute these values into equation 1
α = 1×10⁻⁴/10
α = 1×10⁻⁵ °C⁻¹ .
β = (ΔA/A)/ΔT................... Equation 2
Where β = Coefficient of Area expansivity, ΔA/A = Fractional change in area.
make ΔA/A the subject of the equation
ΔA/A = β×ΔT.......................... Equation 3
But,
β = 2α.......................... Equation 4
Substitute equation 4 into equation 3
ΔA/A = 2α×ΔT................ Equation 5
Given: ΔT = 5°C, α = 1×10⁻⁵ °C⁻¹
Substitute into equation 5
ΔA/A = ( 2)×(1×10⁻⁵)×(5)
ΔA/A = 10×10⁻⁵
ΔA/A = 1×10⁻⁴
Hence the right option is (1) 1×10⁻⁴
the answer to the question is (D)
