Extra - Resistance

Extra: Resistance
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Slide 1: Tekstslide
Natuurkunde / ScheikundeMiddelbare schoolhavoLeerjaar 2

In deze les zitten 26 slides, met interactieve quizzen en tekstslides.

time-iconLesduur is: 60 min

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Extra: Resistance

Slide 1 - Tekstslide

Extra: Resistance

Slide 2 - Tekstslide

Resistance?

Slide 3 - Woordweb

Why is this going well?
A
The outside is made of plastic
B
Only a very small amount of current passes through you
C
The screwdriver is only in one hole at a time

Slide 4 - Quizvraag

Goals
1. After the lesson you will know a formula to calculate the resistance with the voltage and the current.
2. After the lesson you will know the difference in resistance between conductors and insulators. 


Slide 5 - Tekstslide

When is there current
  • Current is moving charge

  • Something completely stuck cannot move

  • In some materials this cargo can move easily, in others it cannot 


Slide 6 - Tekstslide

Conductors

  • Charge is loose
  • Charge can move
  • Conducts electricity 
Isolators

  • Charge is stuck
  • Charge can't move
  • Doesn't conduct electricity 

Slide 7 - Tekstslide

Conductors?

Slide 8 - Woordweb

Insulator?

Slide 9 - Woordweb

What determines how large the amperage will be? 

Slide 10 - Tekstslide

Resistance

Slide 11 - Tekstslide

What happens to the amperage if we put two solid blocks in the middle?
A
The amperage increases
B
Amperage decreases (but not 0)
C
The amperage remains the same
D
The amperage becomes 0

Slide 12 - Quizvraag

Resistance

Slide 13 - Tekstslide

What happens to the current if we make the path less wide?
A
The amperage increases
B
Amperage decreases (but not 0)
C
The amperage remains the same
D
The amperage becomes 0

Slide 14 - Quizvraag

Resistance

Slide 15 - Tekstslide

Resistance
  • Resistance tells us how much a particular electrical component opposes current flow. (How much resistance it offers to current flow)

  • Symbol: R (Resistance)
  • Unit: Ω (Ohm) 

Slide 16 - Tekstslide

Conductors

  • Charge is loose
  • Charge can move
  • Conducts electricity 
  • Low resistance
Isolators

  • Charge is stuck
  • Charge can't move
  • Doesn't conduct electricity 
  • High resistance

Slide 17 - Tekstslide

Formula
Resistance is how much voltage we need for a given amperage 
R=IU

Slide 18 - Tekstslide

The unit of resistance is:
A
Volt
B
Amps
C
Watts
D
Ohm

Slide 19 - Quizvraag

Example
Calculate the resistance of a pocket calculator that has a 1.35 V battery, with a current of 0.200 mA.

Slide 20 - Tekstslide

Calculate the resistance of a pocket calculator that has a 1.35 V battery, with a current of 0.200 mA.
Given:
U = 1.35 V
I = 0.200 A


Asked:
The resistance (R)


Formula:
R = U / I


Calculation:
R = 1.35/0.200 = 6.75 Ω


Answer:
The resistance = 6.75 Ω

Slide 21 - Tekstslide

A current of 0.3 A is measured at a voltage of 18 V. Calculate the resistance.

Slide 22 - Open vraag

A current of 0.3 A is measured at a voltage of 18 V. Calculate the resistance. 
Given:
U = 18 V
I = 0.3 A


Asked:
The resistance (R)


Formula:
R = U / I


Calculation:
R = 18/0.3 = 60 Ω


Answer:
The resistance = 60 Ω

Slide 23 - Tekstslide

The following variables are measured in an electrical circuit:
The amperage is 12 amps, the resistance is 3.5 ohms.

Calculate the voltage.

Slide 24 - Open vraag

The following variables are measured in an electrical circuit:
The amperage is 12 amps, the resistance is 3.5 ohms.

Calculate the voltage. 

Given:
I = 12 A

R = 3.5 Ω

Asked:
The resistance (R)


Formula:
R = U / I  --> U = R x I


Calculation:
U = 3.5 x 12 = 42V


Answer:
The voltage = 42V

Slide 25 - Tekstslide

HomeWork
Read the (PDF)-file: "2tH_ Resistance" (see attachment in Magister and/or Magister ELO)

Make the following exercises (in the same document): 
  • 13, 14c, 15, 17

Slide 26 - Tekstslide