Q.No.159: - Is there any difference between echo and reflection of sound? Explain.

Q.No.159: - Is there any difference between echo and reflection of sound? Explain.

Ans: - No, there is no difference between echo and reflection. Echo can be defined as, when sound is incident on the surface of a medium it bounces back into the first medium. This phenomenon is also called reflection of sound.

Q.No.158:- Two people are listening to the same music at the same distance. They disagree on its loudness. Explain how this could happen?

Q.No.158:- Two people are listening to the same music at the same distance. They disagree on its loudness. Explain how this could happen?

Ans: - If the distance of listener from source is same and medium is also same and they both are disagreeing with the loudness then there is a problem in their ear.

Q.No.157: - A student says that the two terms speed and frequency of the wave refer to the same thing. What is your response?

Q.No.157: - A student says that the two terms speed and frequency of the wave refer to the same thing. What is your response?

Ans: - Speed of a wave is how fast the wave is moving in a medium while the frequency of wave is the number of cycle per unit of time. So these two things are not same.

Q.No.156: - Why must the volume of a stereo in a room with wall-to-wall carpet is turned higher than in a room with a wooden floor?

Q.No.156: - Why must the volume of a stereo in a room with wall-to-wall carpet is turned higher than in a room with a wooden floor?

Ans: - Volume of a stereo in a room with wall to wall carpet must be tuned higher than in a room with a wooden floor because reflection of sound is more prominent if the surface is smooth, and less if the surface is irregular.

Q.No.155: - You can listen to your fried round a corner, but you cannot watch him/her. Why?

Q.No.155: - You can listen to your fried round a corner, but you cannot watch him/her. Why?

Ans: - You can listen your friend round a corner because waves can propagate from solid medium.

Q.No.154: - We can recognize persons speaking with the same loudness from their voice. How is this possible?

Q.No.154: - We can recognize persons speaking with the same loudness from their voice. How is this possible?

Ans: - we can recognize persons speaking with the same loudness from their voice because their quality of sound is different. Quality of sound is the characteristic by which we can distinguish between two sounds of same loudness and pitch. The waveforms of sound produced by persons are different. So their quality is different and they can be distinguished from each other. 

Q.No.153: - Why two tin cans with a string stretched between them could be better way to communicate than merely shouting through the air?

Q.No.153: - Why two tin cans with a string stretched between them could be better way to communicate than merely shouting through the air?

Ans: - When two tin cans are attached with a stretched string then the string becomes a medium that transmit sound wave from one can to the other. String is a solid and it makes a batter medium of transmitting sound wave rather than air. When we shout in air then air carries sound with low speed than a stretched string.

Q.No.152: - Does a fuse in a circuit control, the potential difference or the current?

Q.No.152: - Does a fuse in a circuit control, the potential difference or the current?

 Ans: - Fuse in a circuit controls the excess amount of current.

Q.No.151: - It is impracticable to connect an electric bulb and an electric heater in series. Why?

Q.No.151: - It is impracticable to connect an electric bulb and an electric heater in series. Why?

Ans: - In series connection current remains same and voltage divided according to the resistance of the appliance. When we put electric bulb and electric heater in series then it will divide the voltage which ultimately divided the power double.

Q.No.150: - A certain flash-light can use a 10ohm bulb or a 5ohm bulb. Which bulb should be used to get the brighter light? Which bulb will discharge the battery first?

Q.No.150: - A certain flash-light can use a 10ohm bulb or a 5ohm bulb. Which bulb should be used to get the brighter light? Which bulb will discharge the battery first?

Ans: - If the bulbs are connected in parallel then they will have same brightness because the brightness depends upon the voltage. If the bulbs are connected in series then first bulb will be brighter than the second because in series the voltage drop is different in two bulbs. The bulb which has more resistance will discharge the battery soon.

Q.No.149: - From your experience in watching cars on the roads at night, are automobile head lamps connected in series or in parallel?

Q.No.149: - From your experience in watching cars on the roads at night, are automobile head lamps connected in series or in parallel?

Ans: - The head light of cars are connecting in parallel because their brightness are approximately same. If they are connected in series then first light will be brighter than the second light. In series potential will drop in both headlights. While in parallel potential will remain same and they will have same brightness.

                                                              OR

Head lamps of automobiles are generally wired in parallel. This way, if one headlight is to burn out the others remain switched ON.

Q.No.148: - How many watt-hours are there in 1000 joules?

Q.No.148: - How many watt-hours are there in 1000 joules?

Ans: -

          1kwhr           =         3.6x10⁶J

          1whr             =         3.6x10⁶J/10³

          1whr             =         3.6x10^6-3J

          1whr             =         3.6x10³J

          1whr/3.6x10³         =         1J
          0.000278whr         =         1J

          1000x0.000278watt hr   =         1000x1J

          0.27778watt hr                =         1000J

Q.No.147: - In order to measure voltage in a circuit voltmeter is always connected in parallel. Discuss.

Q.No.147: - In order to measure voltage in a circuit voltmeter is always connected in parallel. Discuss.

Ans: - The potential difference is a measure of voltage difference between two points that’s why we apply voltmeter across two points which will make a parallel connection not a series connection unlike ammeter which has series connection.

Q.No.146: - In order to measure current in a circuit why ammeter is always connected in series?

Q.No.146: - In order to measure current in a circuit why ammeter is always connected in series?

Ans: - According to the definition of electric current. Number of charges passing through a point in a unit time is called electric current. So from this definition we can say that electric current associated to the points of the conductor, that’s why we must apply it in series not in parallel. 

Q.No.145: - Two points on an object are at different electric potentials. Does charge necessarily flow between them?

Q.No.145: - Two points on an object are at different electric potentials. Does charge necessarily flow between them?

Ans: - Electric current flow due to the potential difference. If the object is conductor and there is a potential difference occurs between to different points then electric current will flow. But if the object is insulator then no current will flow.