Tag: electric current and its effects

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Questions Related to electric current and its effects

Multiple choice physics electric current and its effects electric fuse electrical fuse and mcb fuse

......... suggested that the slips should be marked with load lines

  1. Samuel Plimsoll

  2. Einstein

  3. Newton

  4. Archimedes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Fuse should be connected to live / phase wire o fthe circuit. If it is connected to neutral wire , the fuse will melt when excess current flows, but the appliance will still be connected to high potential through live wire. Thus, if a person touches the appliance, he receives shock. 
Hence, choice is (3) 

Multiple choice physics electric current and its effects electric fuse electrical fuse and mcb fuse

Fill in the blank-
An electric fuse works on the ______effect of current.

  1. heating

  2. magnetic

  3. chemical

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Electric fuse work on the principal of heating effect of current . fuse wire is a wire of high resistance and low melting point. when very large current will pass through it, heat will be generated which will melt the fuse wire and break the circuit.By using electric fuses in home we can protect the home appliances from damaging by large amount of current.

Multiple choice physics electric current and its effects electric fuse electrical fuse and mcb fuse

A fuse wire is generally made of

  1. tin

  2. tin-lead alloy

  3. copper

  4. either (a) or (b) above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fuse wire are used to save the home appliances from damagaing by large currents. so they are made up of such materials which have high resistance and low melting point so that they can melt down when unexpected amount of current is passed through.for this work either tin metal or tin-lead alloy will be appropriate. 

Multiple choice physics electric current and its effects electric fuse electrical fuse and mcb fuse

An electric iron draws a current of 15 A from a 220 V supply. What is the cost of using iron for 30 min everyday for 15 days if the cost of unit (1 unit $=$ 1 k W hr) is 2 rupees?

  1. Rs. 49.5

  2. Rs. 60

  3. Rs. 40

  4. Rs. 10
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$I=15 A, V=220 V, t=30 min$
$Energy=P\times t=VIt$
$=220\times 15\times \frac {30}{60}\times 15$
$=3300\times \frac {1}{2}\times 15 W hr$
$=3.3\times kW\times 7.5 hr$
$=24.75 kW hr$
$Cost=24.75\times 2=Rs. 49.50$

Multiple choice physics electric current and its effects electric fuse electrical fuse and mcb fuse

The parameter irrelevant for an electric fuse wire is 

  1. its radius.

  2. its specific resistance.

  3. current flowing through it.

  4. its length.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For fuse wire expression for heat produced is given by eq. is  $H = \dfrac{I^2 \rho}{2 \pi ^2r^3}$
Hence, it is independent on length of fuse wire. Thus, the parameter irrelevant for an electric fuse wire is its length.