Level 4 - Substitution

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• Middelbare school
• havo
• Leerjaar 3

Level 4 - Substitution

Level 4 - Substitution

Substitution means replacing something with something else.

In mathematics you have done this multiple times with x. 

when you know:

and :

You can say that : 

y=2x+2

x=3

y=2x+2=2⋅3+2=8

Solve for y:

y=

y=15x+4

x=​3​​4​​

Solve for y:

y=

y=8x⋅a

x=​2​​b​​

Level 4 - Substitution

If you do the same with variables: 

Now give this a try on the formulas of chapter 1.

y=2x

x=a⋅b

y=2ab

Solve for E:

E =

E=P⋅t

P=U⋅I

Solve for E in joules:

E =

E=P⋅t

P=U⋅I

U = 230 V

I = 5 A

t = 3 s

Don't forget the unit!!!

Level 4 - Substitution

Now we demonstrated the use of substitution into the energy formula. We can improve our substitution skills to the formula of an ideal transformer. 

In an ideal transformer, the power that is lost in the transformer = 0 W. Therefore, the power in the primary coil equals the power in the secondary coil. 

Try substituting with this equation. 

The formula of an ideal transformer is given as:

P​p​​=P​s​​

Power is calculated with the formula:

P=U⋅I

How would you substitute the formula of the power into the formula of the ideal transformer?

P​p​​=P​s​​

=

⋅

⋅

Us

Up

Ip

Is

Congratulations!

You have passed

Level 4 - Substitution

You are a master of calculations by this point! You can prove your strength of mind by completing the bonus level:

http://www.pfnicholls.com/Electronics_Resources/Questions/PowerQuiz.html