Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics reflection of light and shadow beam of light ray and beam ray optics

In a room lighted by an electric bulb, it is found that the shadow of the ceiling fan hung in the centre is falling on a wall opposite to the door. What can you say about the position of the bulb? 

  1. On the wall having the door

  2. On the wall facing the door

  3. On the wall on your right as you enter the room

  4. On the wall on your left as you enter the room
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A.

When we put any object in between the light source it forms a shadow of that object. The closer the object is to the source of the light, the more light it blocks out, so its shadow is bigger. But if the object is further away, it does not block out much light, and so the shadow is smaller.
Therefore, for the shadow of the ceiling fan to be formed on a wall opposite to the door, the electric bulb must be positioned on the wall having the door.

Multiple choice physics reflection of light and shadow beam of light ray and beam ray optics

Which of the following statement is true?

  1. All light is electromagnetic wave

  2. Electromagnetic energy is created only by heat

  3. Matter emits a single, unique photon when it is heated

  4. All of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Option A $\rightarrow $ All light is electromagnetic wave. This option is correct as EM light does not need any medium to travel like EM wave.

Option B $\rightarrow $ Electromagnetic energy created only by heat.
                    This option is false.
Electromagnetic energy can be created in any case of accelerated charge.
Option C $\rightarrow $ When matter is heated many photos are ejected.
                     So this option is false.

Multiple choice physics electric current and its effects heating effect of electric current- uses applications of heating effect of electric current coil and fuse

The heating element in an electric iron is made up of :

  1. nichrome

  2. iron

  3. constantan

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

Answer is A.

Most heating elements use Nichrome 80/20 (80% nickel, 20% chromium) wire, ribbon, or strip. Nichrome 80/20 is an ideal material, because it has relatively high resistance and forms an adherent layer of chromium oxide when it is heated for the first time. Material beneath this layer will not oxidize, preventing the wire from breaking or burning out.
Hence, nichrome is used as heating elements.

Multiple choice physics electric current and its effects heating effect of electric current- uses applications of heating effect of electric current coil and fuse

An electric iron is based upon the principle of

  1. heating effect ofcurrent

  2. magnetic effect ofcurrent

  3. chemical effect ofcurrent

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

An electric iron is based on the principle of heating effect of current that heat is produced in the nichrome wire used in the iron due to the current flowing through it.

Multiple choice physics electric current and its effects heating effect of electric current- uses applications of heating effect of electric current coil and fuse

The overheating of electrical wiring in any circuit due to the flow of large current through it is called _________ of the electric circuit.

  1. over heating

  2. heating effect

  3. cooling effect

  4. see-back effect
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The overheating of electrical wiring in any circuit due to the flow of large current through it is called overloading of electric current.

Multiple choice physics electric current and its effects heating effect of electric current- uses applications of heating effect of electric current coil and fuse

Electrical welding works on principle of:

  1. continuity equation of electric current

  2. heating effect of electric current

  3. heating effect of exothermic reactions

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Electrical working is based on Joule's law, i.e. heating effect of electric current in a conductor.

Multiple choice physics electric current and its effects heating effect of electric current- uses applications of heating effect of electric current coil and fuse

Mark the correct reason/s why nichrome is used for making heating element of electrical appliances. 

  1. Nichrome does not oxidize

  2. Nichrome doesn't burn easily at high temperatures as it has higher melting and boiling point than metals

  3. Nichrome has higher resisistivity and consequently a higher resistance

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

Nichrome is used for making heating element of electrical appliances. Because nichrome does not oxidize and burn easily at high temperature i.e.it has higher melting and boiling point than metals. Thus it does not melt even when a large amount of heat is produced due to passage of current. Moreover, It has higher resisistivity and consequently a higher resistance.Therefore, it will resist the flow of charges more, and lead to development of heat faster.

Multiple choice physics electric current and its effects heating effect of electric current- uses applications of heating effect of electric current coil and fuse

Mark the correct reason why tungsten is used for making filament of electric lamp.

  1. Tungesten oxidises easily

  2. It has low boiling point

  3. It has high melting point

  4. None
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Tungsten is used in electric bulb because it has high melting point and it does not oxidize. Thus tungsten filament does not melt even when a large amount of heat is produced due to passage of current through the filament (via heating effect of current).