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| From: haroonaman | Reply 21 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 16 |
Power
Posted at: Sun Feb 28 17:17:26 2010 (GMT)
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| From: haroonaman | Reply 22 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 17 |
Energy
Posted at: Sun Feb 28 17:18:33 2010 (GMT)
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| From: haroonaman | Reply 23 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 18 |
Distance
Posted at: Sun Feb 28 17:18:52 2010 (GMT)
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| From: haroonaman | Reply 24 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 19 |
Frequency
Posted at: Sun Feb 28 17:19:22 2010 (GMT)
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| From: haroonaman | Reply 25 of 54 | Reply | View replies (2)
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| Subject: Contributed Answer/Explanation to Q. 20 |
The expenditure is =
bulb = 100W
fan = 100W
heater = 1000W
time for each per day = 8 hours.
Power = (100*8) + (100*8) + (1000*8)
= 800 + 800 + 8000
= 9600 Wh
Cost of electricity is = Rs 2 per unit
... Monthly cost = 9600 * 2 * 30
1000
= 96 * 2 * 3
= Rs. 576
Posted at: Sun Feb 28 17:26:41 2010 (GMT)
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| From: haroonaman | Reply 26 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 20 |
The expenditure is =
bulb = 100W
fan = 100W
heater = 1000W
time for each per day = 8 hours.
Expenditure = Power * time
1000
= 1200 * 8
1000
= 9.6 units * 2 rupees
= Rs.19.2
Posted at: Sun Feb 28 17:35:55 2010 (GMT)
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| From: haroonaman | Reply 27 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 20 |
The expenditure is =
bulb = 100W
fan = 100W
heater = 1000W
time for each per day = 8 hours.
Expenditure = Power * time
1000
= 1200 * 8
1000
= 9.6 units * 2 rupees
= Rs.19.2 per day.
Posted at: Sun Feb 28 17:36:29 2010 (GMT)
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| From: haroonaman | Reply 28 of 54 | Reply | View replies (1)
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| Subject: Contributed Answer/Explanation to Q. 21 |
Earthing prevents electrical shocks as the earthing conducts the excess
current to the earth which is neutral and hence prevents shocks.
Posted at: Sun Feb 28 17:39:42 2010 (GMT)
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| From: haroonaman | Reply 29 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 22 |
The particles given out during radioactive decay are alpha and beta
particles and gamma radiations are also given out.
Posted at: Sun Feb 28 17:41:13 2010 (GMT)
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| From: haroonaman | Reply 30 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 21 |
Earthing prevents electrical shocks as the earthing conducts the excess
current to the earth which is at a zero ptential and hence prevents shocks.
Posted at: Sun Feb 28 17:55:42 2010 (GMT)
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| From: haroonaman | Reply 31 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 23 |
When an alpha particle gets decayed we notice that the Atomic number reduces
by 2 while the mass number reduces by 4 and during beta particle decay the
mass number remains a constant while the atomic number increases by 1.
Posted at: Sun Feb 28 17:57:46 2010 (GMT)
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| From: haroonaman | Reply 32 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 24 |
Plants and animals readily absorb Carbon 14 from the carbon dioxide in the
air that they respire and takes about 5800 years to degenerate and hence by
testing the amount of carbon that has been used up people can guess how old
a said tree or animal is.
Posted at: Sun Feb 28 18:00:33 2010 (GMT)
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| From: haroonaman | Reply 33 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 26 |
The pair of pliers will have a mechanical advantage less than one.
Posted at: Sun Feb 28 18:03:13 2010 (GMT)
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| From: haroonaman | Reply 34 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 27 |
A machine whose mechanical advantage is less than one is useful as it will
always act as a force multiplier.
Posted at: Sun Feb 28 18:06:08 2010 (GMT)
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| From: haroonaman | Reply 35 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 28 |
Chemical energy to mechanical energy to potential energy to kinetic energy.
Posted at: Sun Feb 28 18:07:53 2010 (GMT)
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| From: haroonaman | Reply 36 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 32 |
Three characteristics of a musical sound are :
(i) The musical sound always has a definite amplitude.
(ii) The frequency of a musical sound is always less than that for noise.
(iii) The musical sound that is produced by an instrument alwayys has
quality or timbre.
Posted at: Sun Feb 28 18:12:38 2010 (GMT)
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| From: haroonaman | Reply 37 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 33 |
The musical sound is soothing to the year whereas noise is disturbing to the
ear. The sound level of music is low below 30db while the sound level of
noise is above 120db.Music is produced by periodic vibrations whereas noise
is an irregular disturbance.
Posted at: Sun Feb 28 18:22:20 2010 (GMT)
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| From: haroonaman | Reply 38 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 36 |
The distance of the moon from the earth is :
speed of wave = 3 * 108m/s
time = 2.5 seconds
V = 2D
t
3 * 108 = 2D
2.5
... D = 3*108 * 2.5
2
D = 3.75 * 108 m
Posted at: Sun Feb 28 18:38:37 2010 (GMT)
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| From: haroonaman | Reply 39 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 37 |
The speed of light slows down in glass.
Posted at: Sun Feb 28 18:41:21 2010 (GMT)
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| From: haroonaman | Reply 40 of 54 | Reply | |
| Subject: Contributed Answer/Explanation to Q. 38 |
This happens because the density of the medium increases and hence the speed
of light decreases.
Posted at: Sun Feb 28 18:42:11 2010 (GMT)
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