Which of the following statements is true?
2 answers:
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Answer:
Explanation:
The resistance of a wire can be given by the following expression
where R is resistance , ρ is specific resistance , L is length of wire and A is cross sectional area
specific resistance of metals are almost the same . So in the present case ρ and l are same . Hence the formula becomes
R = k / A where k is a constant .
The diameter of wire becomes two times hence area of cross section becomes 4 times or 4A .
Resistance becomes 1/4 times . Hence if resistance of metal wire is R , resistance of silver wire will be R / 4 .
current = voltage / resistance
In case of metal wire
8 x 10⁻³ = V / R
In case of silver wire
I = V / (R / 4 ) , I is current , V is potential difference .
I = 4 x V/R
= 4 x 8 x 10⁻³ A
= 32 mA.
Answer:
c. 2 m/s
Explanation:
The speed of a wave is given by:
where
v is the speed of the wave
f is the frequency
is the wavelength
For the wave in this problem, we have
f = 4 Hz is the frequency
is the wavelength
So, the speed of the wave is