How is an electromagnet different from a magnet?
1 answer:
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Answer:
The correct answer is "22.27 hours".
Explanation:
Given that:
Radioactive isotope activity,
= 490,000 Bq
Activity,
= 110,000 Bq
Time,
= 48 hours
As we know,
⇒
or,
⇒
By taking "ln", we get
⇒
By substituting the values, we get
⇒
⇒
As,
⇒
then,
⇒
⇒
Answer:
A = 1.54 x 10⁻⁵ m² = 15.4 mm²
Explanation:
The resistance of a wire can be given by the following formula:
where,
A = smallest cross-sectional area = ?
ρ = resistivity of copper = 1.54 x 10⁻⁸ Ωm
= resistance per unit length of wire = 0.001 Ω/m
Therefore,
<u>A = 1.54 x 10⁻⁵ m² = 15.4 mm²</u>