# A defibrillator is a device that sends an electrical shock to maintain heart rhythm if a person goes into cardiac arrest. If a defibrillator passes 15

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A defibrillator is a device that sends an electrical shock to maintain heart rhythm if a person goes into cardiac arrest. If a defibrillator passes 15 A of current through the torso of a person in 2 ms, the number of electrons passed to the person is
1. 0.67 × 107 electrons
2. 1.88 × 107 electrons
3. 2.12 × 107 electrons
4. 4.55 × 107 electrons

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Correct Answer - Option 2 : 1.88 × 107 electrons

The correct answer is option 2) i.e. 1.88 × 107 electrons

CONCEPT:

• Electric charge is a fundamental property of matter that causes the matter to experience a force when kept in electric and magnetic fields.
• There are two types of charges possessed by matter - negative charge and positive charge.
• The matter that is neither positive nor negative is said to be neutral.
• The electric charge of the matter comes from the charge carried by electrons and protons at the atomic level.
• The SI unit of electric charge is Coulomb (C).
• Electric current is defined as the charge flowing per unit time.

It is given by:

$I = \frac{q}{t}$

Where I is current, q is the charge and t is the time.

CALCULATION:

Given that:

Current, I = 15 A

Time, t = 2 ms = 2 × 10-3 s

Using $I = \frac{q}{t}$,

The total charge passed to the person, q = It = 15 × 2 × 10-3 = 30 × 10-3 C

Charge of an electron = -1.6 × 10-19 C

Number of electrons in 30 × 10-3 C = $\frac{30 × 10^{-3}}{1.6\; \times\; 10^{-19}} = 1.88 \;\times\; 10^{17}$

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