SPM Questions: Section 2.1, Electricity

Section 2.1 : Analysing Electric fields & charge flows

1. Which graph shows the relationship between potential difference, V, and current, I, for a resistor that obeys Ohm’s law? (SPM03)

ans: A - Ohm's law will give a straight line graph

2. Which diagram shows the correct electric field pattern?(SPM03)

ans:B, lines of field shall move out from +ve charge.

3. Which circuit can be used to determine the resistance of a bulb? (SPM03)

ans: C, voltmeter should be connected in parallel across the bulb, Ammeter must be connected in series

4.The electric current supplied by a battery in a digital watch is 3.0 x 10 A.

What is the quantity of charge that flows in 2 hours? (SPM04)

A 2.5x107C
B 1.5x105C
C 6.OxlO5C
D 3.6x103C
E 2.2x10’C

ans: E, Q=I x t , t= 2 x60 =120s, then use the value of current & substitute it in the formula.

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SPM 2009 : Welcome to Electricity

Dear all..now I’ll be discussing the next chapter Eleccity. B4 I go further, please bear in mind, in form 5, 3 out of the 5 topics comes from a word ElecTRO (electricity,electromagnet, electronics)

Electricity is the fundamentals..u really need to understand tis chapter coz its basic shall be applied in next 2 chapters..lets go deeper

2.1 Analysing Electric fields & Charge flow..

In this subtopic u must be able to:

1. Relate between electron (charge) flow & current:

How??? The flow of electrical charges produces electric current

So what does it mean by electrical charges?

In electrical current, the electrical charges are flowing electrons (-ve charged).

Thus the relationship is ..:If electrons are flowing, current will be flowing as well!

(Note:Check your reference book..refer details on Van Der Graff)

2. The next outcome..u must know how to define Current.
What is current?
Current is the rate of flow of charge
By formula: I = Q/t

I = current , unit is ampere(A)
Q =charge, unit is coulomb (C )
t = time taken (s)

3. Describe an electric field??

• an electric field is a region in which an electric charge experiences a force.
• lines of electric field moves away from + ve charge
• lines of electric field points towards - ve charge.

4. U must also know how to sketch the electric lines with correct direction:

5. U also need to describe the effect of electric field :
Watch these video..then refer yr reference book..or text book(pg46)

effect on pingpong ball

effect on candle flame