Electric Fields
Magnetic Fields
Gravitational Fields
Motors & Generators
Electric Energy
100
What is a test body?
an observable object that can experience a force due to the presence of a field
100
Which direction do magnetic field lines point?
From North to South
100
Gravitational field strength is the number of _____ per _______ a test body will experience at any point.
Newtons per kilogram
100
In a motor, there is always a conversion of energy from ___ to ____
Electrical to mechanical
100
What is the difference between a series & parallel connection?
In series, there is a single path available for electric current, where the charges flow through one device before passing through to the next, but in parallel there is more than one path available for electric current, where the electric current divides, allowing each portion of the current to simultaneously pass through separate devices
200
Why did the running water bend towards the statically charged balloon?
Because water is a polar molecule. The positive charged in the water were attracted to the negative charges in the balloon.
200
What is an electromagnet?
A magnet created around a conductive material by moving electric charges (electric currents) The motion of the charges produces a magnetic field.
200
How does radius correlate to field strength?
As distance from the source increases, the value of gravitational field strength decreases
200
One type of blender requires about 1.5 x 103 C of moving charge to flow through the coils of the motor over a time interval of 6 mins. Calculate the electric current required by this motor.
4.16 A.
200
When resistance is constant, voltage is ____ _____ to current.
Directly proportional
300
The end of a copper wire has a charge of -3.3 C. Determine the strength of the electric field 0.2 m from the wire.
-7.42x10^-10
300
The Earth's magnetic field is a barrier against _______ and _______.
Cosmic radiation & solar wind
300
Earth’s radius has an average value of 6.37 x 10^6 m, while Earth’s mass has a value of 5.98 x 10^24 kg. Calculate the value of the gravitational field strength at Earth’s surface.
9.83 N/kg
300
Describe the difference between AC & DC circuits.
AC: a flow of charges that reverses directions at regular intervals
DC: a flow of charges that does not increase or decrease and flows in a single direction
300
What is the role of a resistor?
A resistor slows or obscures the flow of electric current through a wire
400
As we move away from the point charge, the magnitude of the field ___________ and as we move toward the point charge, the magnitude _____________.
decreases, increases
400
What causes the Earth's magnetic field, according to Geologists?
Geologists suspect that the liquid outer portion of Earth’s core has matter that becomes charged and separates into layers. As the Earth spins, the material spins, creating an electric current that generates Earth’s magnetic field
400
When solar wind collides with our atmosphere, we call it the Northern lights. Solar wind enters through ____________ which occur when the Earth's magnetic field is shifted.
Polar cusps
400
What is a brush?
A brush is a stationary part of a motor or generator that makes electrical contact with the rotating commutator
400
Instagram draws 0.4 A of current from your phone's 4.0 V battery. Determine the resistance
10 Ohms.
500
How do astronauts counter the negatively charged electrons coming from solar wind when doing research on the moon?
The positively charged spheres would be wrapped in insulating wire carrying a large electric current. The flow of moving charges through the coils of wire would exert a force on the incoming electrons before they reached the base.
500
If all things have an electric charge, why does not everything have a magnetic field?
Not all materials are magnetic because in most substances, the orbiting electrons don’t align, so no magnetic field is created
500
The moon has an average radius of 1.74 x 103 km and a mass of 7.35 x 1022 kg. An astronaut in a new lightweight spacesuit has a mass of 100 kg. Determine the force of gravity exerted on the astronaut by the moon’s gravitational field.
162 N
500
Define mechanical energy
the energy possessed by an observable object due to motion or its position; the sum of the kinetic energy and potential energy of an object
500
Explain how when one bulb in a string of Christmas lights does not work, the whole string will not light up. But when one light in your house goes out, the other bulbs do not go out as well.
This is because Christmas lights are in series which only has one path current can take. But a house is in parallel, which means the current can take different paths to reach the other bulbs.