The post office box was a Wheatstone bridge-style testing device with pegs and spring arms to close electrical circuits and measure properties of the circuit under test.
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Why the instrument is called post office box?
The box containing Wheatstone bridge was used in the United Kingdom by engineers in General Post Office, who used it in UK telecommunications to trace electrical faults. Therefore, for historical reasons it was named “Post office box” as it was carried by post office engineers.
Which metal is used in post office box?
The best material for resistance in post box resistor is Manganin. It is an alloy of copper (85%), Manganese (12%) and Nickel (2%).
What is the aim of the post office box experiment?
Post Office Box is helpful in physics experiment to determine the unknown resistance of wires like Constantan and Nichrome etc. With the help of Nvis 6041, the student can learn the principle of Post Office Box and its working. It can determine the specific resistance of different types of wire.
What is post box explain how does it work?
A post box is a numbered box which are available on rent at certain major post offices. Every post box is allocated a number and only postal articles bearing that number are placed into that box.
What is post office Works explain how does it work?
People mail their letters and packages by placing them in a mailbox or taking them directly to the post office. At the post office, postal workers sort the mail by size. Letters go through a machine that cancels the stamps. This means that the machine prints lines over the stamps so that they cannot be used again.
What is measured by using post office box?
A Post Office Box is used to measure an unknown resistance. It is basically a Wheatstone bridge with three arms known as P, Q, and R; while the fourth arm is the unknown resistance, denoted by S.
What is the formula of meter bridge?
ฯ=Lฯr2X ; Where L be the length of the wire and r be its radius.
What is Wheatstone bridge principle?
What is the Wheatstone Bridge Principle? The Wheatstone bridge works on the principle of null deflection, i.e. the ratio of their resistances is equal, and no current flows through the circuit. Under normal conditions, the bridge is in an unbalanced condition where current flows through the galvanometer.
Can we send clothes through post office?
If a parcel contains cloth or woolen material it must be packed in a strong wrapper with an outer covering of stout card-board or cloth. It is suggested to use a wooden or a stout cardboard case according to the nature of the article for packing a parcel.
Can we send sweets by speed post?
No, you cannot send food items through India Post.
How do I add another person to my P.O. box?
- Ask the clerk at the post office where you have the box for the proper form to add a name to the list of people who get mail at that box.
- Fill in the name and physical address on an empty line on the card that’s handed to you.
- Complete any other required information.
Which is the principle followed in PO box?
D) Principle of wheatstone bridge. Hint: Post office box is a wheatstone bridge style testing device with pegs and spring arms in order to close the electrical circuit to measure the properties of the circuit under test. Basically, a post office box is a measuring device.
What is half deflection method?
The half deflection method is the method by which an internal resistance of a cell can help in evaluating value which is considered as high. The deflection of half is considered as a value obtained along with the cell alone.
How can potentiometer be used to calculate potential difference?
The potentiometer is an instrument used for measuring the unknown voltage by comparing it with the known voltage. It can be used to determine the emf and internal resistance of the given cell and also used to compare the emf of different cells. The comparative method is used by the potentiometer.
Why post box is red in colour?
In early Victorian era the color of post box was Green in Britain. Then during the mid 19th century it was changed to Red. So with the Britishers the color of post box also came to its colonies like India, Australia, etc.
What is the colour of post box?
However, there is some variety indicating uncertainty as to the correct green to be used. Royal Mail have agreed that, only where there is historic precedent, will post boxes be painted in any colour other than the current official, standard colour- red.
When was the post box invented?
Channel Islands Box (1852) The first post box installed by the British Post Office.
What is the main function of post office?
The primary function of Post Office is collection, processing, transmission and delivery of mail.
What is the importance of post office?
Postal services are also valuable to the government of some countries. They use the services to coordinate with other offices- to send notices, memos, and other documents. It is useful especially to places that are hard to reach. They event sent packages and parcels from one post office to another.
How many types of post office are there?
It is basically classified into 3 types, namely โ Head Post office, Sub Post Office and Branch Post Office.
Which is more accurate voltmeter or potentiometer?
Potentionmeter measures the potential difference more accurately than a voltmeter, because the potentionmeter.
What is null point in meter bridge?
In a meter bridge experiment, a null point is obtained at 20 cm from one end of the wire when resistance x is balanced against another resistance y. If x In a metre bridge, wires of nichrome, manganin and constantan are used because it has high resistance and low-temperature coefficient of resistance. The jockey is used to slide on the bridge wire. It is a metal rod with one end as knife edge. Now adjust the value of resistance in the resistance box and slide the jockey along the wire. This process is to be done until the galvanometer shows a zero or null deflection.Which wire is used in meter bridge?
Why jockey is used in meter bridge?