Question
In a newly opened estate the planner had a specified number of occupants for the estate and the electricity board gave them a transformer that could serve the specified number of occupants However the number of occupants eventually increased beyond the planned number due to sub division of the plots and the transformer could not serve the population any more. All people started to complain that their electrical appliances, security lights and security alarms are no longer working and this has brought insecurity in the estate. Hint; Power input of the transformer=12000W, voltage output=240V and the output current= 20A Task As a physics student; (a) Explain why the transformer could no longer serve the big population of the estate. (b) Suggest the possible causes of power losses in a transformer and how they can be minimized. (c) Explain how an electric bell (alarm)works in order to alert people.
Answer
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Abigail
Elite · Tutor for 8 years
Answer
### (a) The transformer could no longer serve the big population because its power output capacity (4800 W) is insufficient to meet the increased demand.### (b) Possible causes of power losses in a transformer include copper losses, iron losses, leakage flux, dielectric losses, and stray losses. These can be minimized by using better materials, improved design, and construction techniques.### (c) An electric bell works by using an electromagnet to attract a metal armature, which repeatedly strikes a bell to produce a ringing sound.
Explanation
## Step1: Transformer Capacity Analysis### The transformer has a power input of
, a voltage output of
, and an output current of
. The power output can be calculated using the formula
, where
is the current and
is the voltage. Therefore, the power output is
. This indicates that the transformer is not efficient enough to handle the increased load, which is why it can no longer serve the larger population.## Step2: Causes and Minimization of Power Losses in Transformers### Power losses in transformers can occur due to several reasons: 1. **Copper Losses**: Due to the resistance of the windings, minimized by using thicker wires or better conducting materials.2. **Iron Losses**: Due to hysteresis and eddy currents in the core, minimized by using high-quality core materials and laminating the core.3. **Leakage Flux**: Not all magnetic flux links both primary and secondary windings, minimized by better core design.4. **Dielectric Losses**: Due to the insulation material, minimized by using high-quality insulation.5. **Stray Losses**: Due to leakage inductance and capacitance, minimized by proper transformer design and construction techniques.## Step3: Working of an Electric Bell (Alarm)### An electric bell works on the principle of electromagnetism. When the bell is connected to a power source, current flows through the electromagnet, creating a magnetic field. This magnetic field attracts a metal armature attached to a hammer. As the armature moves, it breaks the circuit, causing the electromagnet to lose its magnetism and the armature to return to its original position. This cycle repeats rapidly, causing the hammer to strike the bell continuously, producing a ringing sound.