Home » Posts tagged 'Electronics and Electrical'
Tag Archives: Electronics and Electrical
photodiode sensor
i want to make a sensor using photodiodes. here photodiodes are connecting parallel and to each photodiode i have to put a load resistance. how can we calculate the value of photo diode? on what basis we can design the load resistance value. i am applying a voltage of 2.5 volt . Is there any method for finding the load resistance value of a photo diode ?
Asked Indira
Share the knowledge
Single phase, two phase, three phase and multiphase electric generators – which one is more efficient?
I started referring to the above issue when one students asked, “Why do we use three phase generation of power and not two phase or four phase?”
Three-phase has properties that make it very desirable in electric power systems:
The phase currents tend to cancel out one another, summing to zero in the case of a linear balanced load. This makes it possible to reduce the size of the neutral conductor because it carries little to no current; all the phase conductors carry the same current and so can be the same size, for a balanced load.
Power transfer into a linear balanced load is constant, which helps to reduce generator and motor vibrations.
Three-phase systems can produce a rotating magnetic field with a specified direction and constant magnitude, which simplifies the design of electric motors.
Refer the following links for more …
http://en.wikipedia.org/wiki/Two-phase_electric_power
http://en.wikipedia.org/wiki/Polyphase_system
http://en.wikipedia.org/wiki/Three-phase_electric_power
Related articles
Share the knowledge
Current Electricity – Drift Velocity based numerical
Two different wires X and Y of same diameter but different materials are joined together in series across a battery . If the number density of electrons in X is twice that in Y . Find ratio of drift velocity of electrons in two wires .
Asked Kavita
Answer:
In series combination, the current is the same.
I = nAev
=> n1v1 = n2 v2
=> v1:v2 =n2:n1
Related articles
Share the knowledge
Transformers
Please explain what is transformer and tell what is the reason behind the working of transformer that it reduces potenial when current is high and increases potential when current is low?
Explain widely and deeply with concepts.
Answer:
Transformer is a device based on mutual inductance and is used to change the voltage of alternating (or varying) current. There are two types of transformers – stepup and stepdown.
A step-up transformer increases the voltage as the step-down transformer decreases the ac voltage.
When a transformer changes the alternating voltage, it is not adding any power, it only transforms the voltage.
As power is the product of voltage and current, as voltage increases, the current decreases. (and vice versa)
The following links will help you understand transformers in great detail.
- http://www.physlink.com/education/askexperts/ae427.cfm
- http://en.wikipedia.org/wiki/Transformer
- http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/transf.html
- http://www.nuffieldfoundation.org/practical-physics/explaining-how-transformer-works
Share the knowledge
V proportional to I or I proportional to V in Ohm’s Law?
Why we used I proportional to V?
Can we write V proportional to I also?
Answer:
Both are ok. If we are changing the current and observing the voltage, then it is V∝ I
If we are changing the voltage and observing the current, then
I∝ V
In general, we write
the dependent variable proportional to the independent variable
dependent variable = the quantity measured by us
independent variable = the quantity fixed by us
Share the knowledge
Strength of a cable and number of strands
Is the strength of a single strand of a steel cable proportionate to the entire cable? meaning if lets say a cable was made up of 100 strands and could lift a hundred pounds, would each thread be able to lift a pound, or does the cable as a whole become stronger?
AJ asked
Answer:
The strength of the cable increases with increase in the number of strands.
Share the knowledge
Resistance of Transmission lines
A high voltage transmission line has an aluminum cable of diameter 3.0 cm , 200 km long . What is the resistance of this cable?
Harleen asked
Answer:
Use the relation R = ρ l/A
A= πr2 =πd2/4
= 3.14 x 3 x 10-2x 3 x 10-2/4
ρ= 2.82×10−8 ohm m
l = 200km = 200000 m = 2 x 105m
You can now just substitute the values and get the answer.
Share the knowledge
AskPhysics Q&A
- Answered: which theory state that every molecule of magnetic substance is a tiny magnet
- Answered: Why machine get jammed in winter?
- Answered: what is a laser?
- What do you mean by reversible and irreversible process
- Why do we Study electric field along axial line?
- How Quantum Field Theory explains triboelectricity?
- Important topics to study for NEET Physics
- What are the most important topics in JAM Physics?
- If the size of the unit decreases by 20% the% change in the numerical value is
- Why is easier to hammer a sharp nail into wood than a blunt one?