3T circuits 5.2

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Slide 1: Tekstslide
NatuurkundeMiddelbare schoolvwoLeerjaar 3

In deze les zitten 16 slides, met interactieve quizzen en tekstslides.

time-iconLesduur is: 90 min

Onderdelen in deze les

Slide 1 - Tekstslide

What about today?
1. Discuss the homework from §1
2. What is resistance?
3. Creating the formula ourselves
4. How about varying resistance?
5. Work on some exercises (+ discussing difficult ones)

Slide 2 - Tekstslide

Questions about the homework?

Slide 3 - Tekstslide

Slide 4 - Tekstslide

Slide 5 - Tekstslide

Learning objectives
  • You can do calculations using the relation between resistance, voltage and current.
  • You can explain the influence of temperature on the resistance.
  • You can explain the difference between an 'ohmic resistor', an 'NTC' and an 'LDR'.

Slide 6 - Tekstslide

What is resistance?

Slide 7 - Tekstslide

Let's try to find a relation between the voltage (U) and current (I)!

Slide 8 - Tekstslide

The graph

Slide 9 - Tekstslide

Ohm's law





In words:
"The voltage and current are directly proportional."
R=IU
Resistance      in [Ω]
Voltage in [V]
Current in [A]

Slide 10 - Tekstslide

We just used a resistor to get a graph with a
straight line. Is this true for every device? (So does
every device have a straight line as well?)
Yes
No
I dunno

Slide 11 - Poll

Results of the light bulb

Slide 12 - Tekstslide

Types of resistors
Ohmic resistor:  The resistance is always the same, so a straight                                     line in the U-I-diagram.
Light bulb: The resistance increases when the temperature                                  increases (so if both U and I increase).
NTC: The resistance decreases when the temperature increases

LDR: The resistance will be lower when more light falls on it.

Slide 13 - Tekstslide

LDR
NTC

Slide 14 - Tekstslide

A LED is connected to the electrical grid in
your home. You measure a current of
0.25 A. Calculate the resistance of the LED.

Slide 15 - Open vraag

Let's work on some exercises
Read: p. 75-78
Make: 2, 3, 4, 6, 7

Slide 16 - Tekstslide