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Physics Revision Term 1 test (5/3/18)
Karten in diesem Stapel (36)
- 1What is conventional current flow?Positive to negative charge
- 2What is the formula to work out resistance in series?RT = R1+R2...+RN
- 3The unit of chargeq, the coloumb
- 4Properties of currentUnit: I
The number of electrons per second carried through a conductor - 5Properties for voltageUnit: V
The potential difference between negatively charged and positively charged objects - 6Properties of resistanceUnit: R
Property of material that helps prevent the flow of electrons in it. - 7What is static electricity?Static electricity occurs when there is a build up of electric charge on the surface of a material.
- 8Why is static electricity so called?Static electricity is so called because the charges don't move. The electricity we use everyday involves moving charges.
- 9How is static electricity caused?Static electricity is caused when certain materials are rubbed against each other and electrons are stripped off.
- 10What do electrons have to do with static electricity?Electrons are stripped off one material and onto another.
- 11Materials with extra electrons......are negatively charged.
- 12Materials that have lost electrons......become positively charged.
- 13What are the 2 types of current (acronyms and names)?DC - Direct Current
AC - Alternating Current - 14Where is AC current commonly found?In power sockets in the wall.
- 15Give one example (probably the main example) of where direct current is usedMain example: Batteries
- 16Alternating currentFlow of charge back and forth, changing its direction many times in a second (50-60 Hz)
- 17Direct CurrentFlow of charge always in one direction
- 181 Hertz (Hz)1 Hertz (Hz) = 1 cycle per second
- 19The Central ConceptClosed circuits
- 20Ohm's Law states that:Ohm's Law states that electric current flowing through a wire is directly proportional to the potential difference across its ends, provided its temperature remains the same.
- 21What does 'directly proportional' mean?Directly proportional means if one variable is always the product of the other variable and a constant.
eg) Voltage (V) is variable 1
Current (I) is variable 2
Resistance (R) is a constant (K)
Variable 1 = Variable 2 x constant
Voltage = Current x Resistance
V = IR
Hence Ohm's Law - 22In a parallel circuit, current is......split
- 23In a series circuit, voltage is......split
- 24In a series circuit, current......remains the same
- 25In a parallel circuit, voltage......remains the same
- 26Another equation for current is:I = Q/t
(total charge per second) - 27In the equation I = Q/t, what does each variable mean?I = Current
Q = Total charge
t = time - 28Another formula for voltage is:V = w/q
(joules per charge) - 29In the equation V = w/q, what does each variable mean?V = Voltage
w = work done, energy, joules
q = charge - 30List as many formulas for POWER as you can:More common formula:
P = w/t, or work done divided by time (seconds)
Also known as joules per second.
Other formulas for Power:
P = VI (watts)
P = w/t (watts)
P = V squared / R
P = R x I squared
P = F.d/t (work done/energy)
or P = F x V - 31What does Kirchhoff's 1st Law state?The sum of total current equals to 0
eg) I (in) = I1+I2+I3...+IN - 32What does Kirchhoff's 2nd Law state?The sum of total voltage equals 0.
eg) V (in) = V1+V2+V3...+VN
Each path in a parallel circuit is one loop for voltage.
eg) There are 4 paths in a parallel circuit. The voltage in each path is 12 volts. One path is therefore 12 volts. With that being said, in series, voltage is split, so if there are 2 equal resistors in the now series path, the voltage will split up into 6 volts each. If the resistors are of different value, the voltage will vary, however, they will always add up to 12 volts at the end of the circuit. - 33Explain how VI = w/t using other known formulasV = w/q
I = Q/t
therefore P = w/q x Q/t
= w/t
therefore VI = w/t
OR
V = w/q
therefore w = Vq
I = Q/t
therefore t = Q/I
So P = w/t
= Vq x I/Q
= VI
therefore VI = w/t - 34Unit for energy:Joules (J)
- 35Unit for time:Seconds (s)
- 36Unit for power:Watt (w)
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- Beschreibung
- Revising for physics 1 day before the test. 5/3/18
- Erstellt von
- Eagan Morrell
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