Lines of Force around an Electromagnet. ... The magnetic field strength of an electromagnet is therefore determined by the ampere turns of the coil with the more turns of wire in the coil the greater will be the strength of the magnetic field.
Answer:
20 Ω
Explanation:
Voltage, current, and resistance are related by Ohm's law:
V = IR
40 V = (4 A) R
R = 10 Ω
The total resistance of the circuit is 10 Ω.
Resistors in parallel have a total resistance of:
1/R = 1/R₁ + 1/R₂
1 / (10 Ω) = 1 / (20 Ω) + 1/R₂
R₂ = 20 Ω
<h3><u>Answer;</u></h3>
A. 4
<h3><u>Explanation;</u></h3>
- <em><u>The period of a wave or periodic time is the time taken for a complete oscillation to occur. </u></em>For example its is the time taken between two successive crests or troughs.
- <em><u>The beats or oscillation that occur in one second represents the frequency. Frequency is the number of complete oscillations or beats in one second in a wave.</u></em>
- Frequency, measured in Hertz is given by the reciprocal of the periodic time.
- Thus; <u><em>Frequency or beats per second = 1/(1/4) = 4</em></u>
- <u><em>Hence , 4 beats per second</em></u>
Answer:
i) 21 cm
ii) At infinity behind the lens.
iii) A virtual, upright, enlarged image behind the object
Explanation:
First identify,
object distance (u) = 42 cm (distance between object and lens, 50 cm - 8 cm)
image distance (v) = 42 cm (distance between image and lens, 92 cm - 50 cm)
The lens formula,

Then applying the new Cartesian sign convention to it,

Where f is (-), u is (+) and v is (-) in all 3 cases. (If not values with signs have to considered, this method that need will not arise)
Substituting values you get,
i) 
f = 21 cm
ii) u =21 cm, f = 21 cm v = ?
Substituting in same equation
v ⇒ ∞ and image will form behind the lens
iii) Now the object will be within the focal length of the lens. So like in the attachment, a virtual, upright, enlarged image behind the object.