Final 1 Flashcards
What Direction is the Force of a current-carrying wire?
Perpendicular or at right angle to both the MF and the Current.
If your fingers are pointing upward and your thumb is pointing to the right, what direction is the force?
Towards you
Alternating Current
Current that’s direction changes over time. The voltage across the resistance goes up and down.
Transformer
A device that uses electromagnetic induction to change the size of a voltage for an alternating current.
Induced Electromotive Force
The generation of a potential difference in a coil due to the changes in the magnetic flux through it measured in Volts
Kirchhoff’s First Law (Junction or node Law)
The sum of currents flowing into the node is equal to the sum of currents flowing out of the node
Kirchhoff’s Second Law (the loop)
The sum of all voltages around a closed loop in any circuit must be equal to zero, meaning the net change in voltage should be zero
Magnetic Flux
The number of flux lines through a certain area
Electromagnetic Induction
The process of generating a current through a wire in a circuit in a mag. field
Voltage Divider
A circuit that produces a potential difference that is less that what its source provides
What would removing a resistor in a parallel circuit affect?
The overall current but not the current in another branch because current depends on the voltage, which is equal everywhere, and the resistance of each individual resistor, which is different in every branch.
How would adding more devices in a series affect the current?
It will decrease the current,
How does a light meter use a photoresistor?
photoresistor is a sensor that changes its resistance when light shines on it. The resistance generated varies depending on the light striking at his surface. A high intensity of light incident on the surface will cause a lower resistance, whereas a lower intensity of light will cause higher resistance.
Short Circuit
When the current used exceeds the current supplied causing it to malfunction or light on fire due to the extra thermal energy from the extra current
Types of Safety in Circuits
1) Fuse: Melts when the current exceeds its limit
2)Circuit Breaker: An automatic switch that disconnects the current flow by opening when it detects too much current
3)Ground Fault interrupter: Breaks the current when it detects a new path or a difference in the current implying either a fire, extra demand or electronization.
Power (watts) Formula
P = I X V
Ammeter
- Measures Amps
- Placed in Series
-Low resistance
Voltmeter
-measures Voltage
- Placed in Parallel
- High resistance
*Connecting it across a resistor will lower the potential difference
Polarization
The alignment of domains
Solenoid Facts
- Each loop in a solenoid has its own MF but together they are in the same direction
- A computer has a solenoid in its hard-drive to record information on a spinning desk
Speed in Electric Motors
Can be controlled by varying the frequency at which the current alternate
Levetation
The repulsion of two objects that one of them carries an opposing magnetic field due to the it being induced by an EMF opposing the original one due ot Lenz’s law, Which causes the two of them to repel since they would be facing ear other’s like poles. The MagLev trains use it to elevate the trains off of the tracks
Lez’s Law
It states that a induced magnetic field should always oppose the direction of its original magnetic field to avoid the line up of the two magnetic field that will result in infinite, never-ending cycle of inducing the magnetic flux and current which oppose the law of Energy Reservation
How Does Lenz’s Law affect Generators and Motors?
For generators, the induction of an opposing magnetic field will result in a higher resistence which will slow down the movement of the armature.
For Motors; it will help decrease the initial high current.
Eddy’s Currents
They are loops and whirpools of electrical current that are induced by the fluctuation of a magnetic field whihc they will run perpendicular to.
The Eddy Current Damping Effect
It’s the slow doen of movement due to the high resistance that the extra produced currents results in, it’s used to slow down trains and roller coaster. To reduce its effect, motors use thin materials that can not hold high amount of eddy currents.
Self-Induction
The ability of a wire or a coil to produce an opposing EMF if it faces a change in current that result in a magnetic field flux to decrease or increase the change that happens.
Change Change Opposing
In —–> In ——-> EMF
Current Flux Produced
Isolation Transformers
Transformers have no power of stepping up or down, so zero change i the input. They are used for safety reasons mostly
Mutual Inductance
And EMF and Current produced in a coil due to a change in another coil.
How does A Synchrotron apply the rules of magnetic fields
It had a magnetic force which causes the charges to accelerate and move in a circular path
