2015 - JAMB Physics Past Questions and Answers - page 5
Note: the strength of an electromagnet increase with a decrease in the number of turns of the coil other are(ii) increase in current with in the coil
Users' Answers & CommentsR0 = 7Ω , R1 = 7.2 Ω, R2 = 7.5 Ω, Tx = ?
[(X – T100°C) ÷ (R1 - R0)] = [(T100°C – T0°C) ÷ (R2 - R0)]
[(Tx – 0) ÷ (72 – 7)] = [(100 – 0) ÷ (7.5 – 7)]
Tx/0.2 = (100 ÷ 0.5)
Tx = [(0.2 × 100)] ÷ 0.5
= 20/0.5 = 40°C
Users' Answers & CommentsI. Taking it to a high altitude
II. Dissolving a salt into it
III. Heating it in a sealed flask
IV. Increasing the rate of heat supply
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The boiling point of water can increase, if
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Heating it in a sealed flask
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The rate of the heat supply is increased
I. Using a soft iron ore
II. Laminating the iron core to reduce energy loses due to eddy current
III. Designing an efficient iron core
Fig (I) (II) (III) are they in which a transformer was designed to reduce an energy loses by reducing through this collective designed or efforts
Users' Answers & CommentsMercury and alcohol are often used in THERMOMETER
Note:Water is never allowed to be used in thermometer because, it doesn’t expand uniformly
Users' Answers & CommentsFor maximum range (Rmax)
Rmax = U2 ÷ α g where Rmax = 36m, U2 = ?, g = 9.8m/s2
36 = U2 ÷ 2 × 8.8
U2 = 36 × 2 × 9.8m = 705.8
√U = √ 705.6 = 26.5 (squaring both side)
u= 26.5m/s, U = 27m/s (Approx.)
The speed of projection = 27m/s2
Users' Answers & CommentsNote: relative density has no S.I unit
∴ Relative density = weight of substance ÷ weight of equal volume of water
RD = w1 ÷ (w1 – w2) (no S. I unit)
Users' Answers & CommentsGas thermometers are considered best for use to achieve an accurate temperature than others, such as liquid in glass thermometers such as mercury, clinical and alcohol thermometer
Users' Answers & Comments