Static Electricity

Elementary Charge

Quantized charge, electrons, protons, and the fundamental unit of charge

Elementary
Charge

Elementary Charge lesson illustration

 

Could an ion ever have a charge of -1.5 or +4.5 ?

 

Show Me The Physics
YouTube Channel

 

Where did the charge go?

Show Me The Physics
YouTube Channel

School blocks YouTube? Use the file below.

Where_did_the_charge_go

 

 

 

 

 

The charge went into the glass.

See Leyden Jar at Wikipedia

 

 

Fill in The Blanks Conservation of Charge Notes

 

E) Elementary Charge - smallest charge known to exist in nature

 


 Charges come in whole number multiples of

1.6 x 10-19 Coulombs

 

p  

+1.6 x 10-19 C

(Reference)


e-

-1.6 x 10-19 C



(Reference)

 

 

Ex) Object has 4 p, 1 e-, charge?

 

 

 

+ 3 elem. charges or ...

 

 

+ 4.8 x 10-19 C

 

Ex) How many excess charges are there in an object with a charge of -9.6 x 10–19 C?

 

 

 

 

6 excess electrons

 

 

 


Divide by
1.6 X 10-19 Coulombs

To find # of

elementary charges

 

 

Ex) A metal sphere -1.1 × 10-6 C. How many more electrons than protons are on the sphere?

 

Elementary Charge lesson illustration
a) 1.8 × 1012 b) 5.7 × 1012
c) 6.9 × 1012 d) 9.9 × 1012

 

Ratio

 

1 elementary charge

1.6 X 10-19 coulombs

 

 

Divide by 1.6 × 10-19 C

 

 

 

Scientific Notation/TI83Plus

 

-1.1 × 10-6 C

(1.6 × 10-19 C)

 

 

c) 6.9 × 1012 electrons

 

 

 

 

Ex) An object can  have a charge of

Elementary Charge lesson illustration
a) 3.2 x 10-19 C b) 4.5 x 10-19 C
c) 8.0 x 10-19 C d) 9.6 x 10-19 C

 

 

 

 

 

b) 4.5 x 10-19 C not possible


(not an even multiple
of 1.6 x 10-19 C)

 

 

 

 

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Check Your Understanding

5 quick questions — pick an answer to see if you’re right.

1. What is the elementary charge?

2. An object has 4 protons and 1 electron. What is its net charge?

3. An object has a charge of −9.6 × 10⁻¹⁹ C. How many excess electrons does it have?

4. Which charge is NOT possible for an object?

5. Could an ion have a charge of −1.5 elementary charges?

NYSSLS Regents Practice · Electricity · Quantized Charge

Finding the Smallest Unit of Charge

Students measured the charge on several tiny charged plastic beads. Their results are shown in Table 1.

Table 1: Measured Charges

BeadCharge (C)
13.2 × 10−19
24.8 × 10−19
38.0 × 10−19
41.6 × 10−19

Which conclusion is best supported by the data?

▶ Want a challenge? Open 6 more Regents-style questions  (harder · mixed formats)

Challenge score: 0 / 6

Substitute values

C1. A dust particle loses 3.0 × 1012 electrons. Substitute numerical values into a mathematical representation that can be used to determine the magnitude of the particle’s charge. Then calculate the charge.

q = ( × 1012)( × 10−19 C) = × 10−7 C
Multiple choice

C2. An object has a charge of −1.6 × 10−17 C. How many excess electrons does it have?

Support or Refute · Justify

C3. A fifth bead is measured to have a charge of 2.4 × 10−19 C. A student makes the following claim.

Claim: The fifth bead’s measured charge is consistent with the data in Table 1.

Place a check mark in either the Support or Refute box. Justify your response using a mathematical relationship.

Select all that apply

C4. Place a check mark in three boxes to indicate the charges that could be measured on a plastic bead.

Multiple choice

C5. What is the charge of a proton?

Constructed response

C6. Another student points out that every charge in Table 1 is also a whole-number multiple of 0.80 × 10−19 C, so the smallest unit of charge might be 0.80 × 10−19 C instead of 1.6 × 10−19 C. Describe the additional evidence that would show the smallest unit is 1.6 × 10−19 C.

Coulomb’s Law →