2 * 10 ^ 20 charges move in a wire when we connect a 3.7 V battery. Ho

[amizy9990]

Homework Statement

2 * 10 ^ 20 charges move in a wire when we connect a 3.7 V battery. How much work has the battery done?

Relevant Equations

W=Q*V

W=Q*V

2*10^20 Q * 3,7 V= 7,4*10^20 ??

 

[BvU]

How much is the charge of one charge carrier ?

 

[amizy9990]

2*10^20

 

[BvU]

In what units ?

 

[BvU]

2*10^20

No, there are 2 10²⁰ charge carriers. What is the charge on ONE of them ?

 

[amizy9990]

the unit is Q

 

[amizy9990]

No, there are 2 10²⁰ charge carriers. What is the charge on ONE of them ?

2Q?

 

[BvU]

what is Q ? How many of what units ?

 

[BvU]

You must be familiar with elementary charges by now ?

 

[amizy9990]

what is Q ? How many of what units ?

Q is charge. What do you mean?

 

[Gordianus]

A bit of help. Look for electron's charge.

 

[BvU]

Q is the symbol we use for charge. The SI unit for charge is the Coulomb.

In your exercise, the 2×10²⁰ is the number of elementary charge carriers that were moved. Each of them carries 1.6×10⁻¹⁹ Coulomb, so the charge Q that was moved is 2×10²⁰ times 1.6×10⁻¹⁹ Coulomb.
The work done is 3.7 V times Q

 

[amizy9990]

thanks, i forgot to calculate with electron's charge