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PS-6 Test Review
What must increase to effect the KE of an object the most?
The velocity because it is squared in the formula… KE= ½ mv2
According to the law of conservation of energy, energy in the universe cannot be created or destroyed, therefore it is _________.
transferred
How much work is done when a 10N force is applied over a 3 meter distance?
W = f x d = 10N x 3m = 30 J
What are the requirements to do work?
An object must move
The motion of the object must be in the same direction as the applied force on the object
You rub a balloon against your sweater: What charge does the balloon have and why?
Negative – it picked up electrons from your sweater
What charge does the sweater have and why? Positive – it has less electrons after
transferring some to the sweater By what method was charge transferred?
friction
What is the difference?
Charge by conduction Charging an object by contact
Charge by induction Charging an object by holding a
charged object near it
Which of the above is lightning and why? Charge by induction…the clouds and
the ground don’t touch each other
What is static electricity?
The accumulation of excess electric charges on an object
Static meaning no motion
Electroscope
What does it detect? An unknown electric charge
When the leaves spread apart what has happened? The charges are the same and repel
How does it detect an unknown charge? leaves come together if the charges
are different (attract)and will spread apart if like charges (repel)
Electric Current What is it?
The flow of electrons through a conductor How is it measured?
Amperes (A) ______ is the force or push for electrons in a circuit
and is measured in ______. Voltage, Volts (V)
______ is electrical friction and is measured in _________. Resistance, Ohms ()
Ohm’s Law
What is it? The current in a circuit = voltage
divided by the resistance
What is the current in a circuit with a 6 volt battery and 2 ohms of resistance? I = V/R = 6V / 2 = 3 A
Electric Circuits A _______circuit has one path for electrons
to flow. Series
A _______ circuit has more than one path for electrons to flow. Parallel
Series Circuit
What happens if a bulb is removed? All the lights go out – open circuit
If you add a bulb what happens to: Voltage - increases Current - decreases Resistance - increases
Parallel Circuit What happens if a bulb is removed?
The other bulbs stay lit & are brighter If a path is added, what happens to: Voltage – Stays the same Current - Increases w/ each path Resistance – decreases w/ each path
Resistance in a circuit is effected by what 3 things? Large diameter – less resistance Long wires – greater resistance Increase in temperature – increase
resistance
Electromagnet
What is it? Electricity runs through a wire and
causes a magnetic field
What can be done to increase it’s strength? Coil more wire around the object
In electromagnetic induction, electric current is produced when a loop of wire is moved through a ___________. Magnetic field
What is the difference between AC and DC current?
AC =current moves back and forth
DC = flows in one direction