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Read the following passage and answer the accompanying questions - Leaving Cert Physics - Question 11 - 2017
Question 11
Read the following passage and answer the accompanying questions. Telecommunications have been among the most influential technologies in history. Communications ac... show full transcript
Worked Solution & Example Answer:Read the following passage and answer the accompanying questions - Leaving Cert Physics - Question 11 - 2017
Step 1
Draw a labelled diagram of an arrangement of apparatus that could be used to demonstrate the principle that a current-carrying conductor experiences a force in a magnetic field.
Answer
To demonstrate this principle, you could draw a diagram including:
- A power supply connected to two parallel conductors
- The conductor suspended in a magnetic field (indicated by magnetic field lines)
- Indicate the direction of current flow through the conductors and the resulting force acting on them. Ensure to label all parts clearly.
Step 2
Explain how this principle is used in the definition of the ampere.
Answer
The principle states that when a current flows through two conductors placed parallel to each other in a magnetic field, they experience a force. The ampere is defined as the amount of current that, when flowing in two parallel conductors one meter apart in a vacuum, produces a force of 2 x 10^-7 N per meter.
Step 3
Draw a circuit diagram of a Wheatstone bridge.
Answer
The circuit diagram should include:
- Four resistors arranged in a diamond shape.
- A galvanometer connected between the midpoints of two opposite sides.
- An ammeter in the circuit to measure current flow.
- Ensure to label all components, including the resistors and galvanometer.
Step 4
Why did Telstar not allow transatlantic signals to be transmitted constantly?
Answer
Telstar operated in a geostationary orbit, which meant it was not always positioned over the same area on Earth. This caused interruptions in the transmission, as it needed to be aligned properly to maintain constant communication. Additionally, the satellite's orbiting nature limited the timeframe during which signals could be transmitted.
Step 5
Calculate the radius of orbit of Telstar.
Answer
To calculate the radius of orbit, we can use the formula for gravitational force:
Given:
- Period (T) = 2.6 x 60 x 60 seconds
- Mass of Earth (M) = 6.0 x 10^24 kg
Using these values, we would rearrange and calculate:
where substituting in the known values yields:
Step 6
With the aid of a labelled diagram, explain how light is transmitted through optical fibres.
Answer
Light transmission in optical fibres occurs through total internal reflection. In your diagram:
- Include a section of optical fibre with the core and cladding labeled.
- Show the angle of incidence being greater than the critical angle (indicating total internal reflection).
- Explain that as light enters the fibre, it hits the core-cladding boundary at a suitable angle, ensuring all light reflects internally without loss.
Step 7
Light travels a distance of 5500 km along the Hibernia Express between London and New York. Calculate the refractive index of the glass used in the cable.
Answer
To find the refractive index (n), we can use the formula: where:
- Length of travel = 5500 km = 5.5 x 10^6 m
- Speed in vacuum (c) = m/s
- After deriving v (the speed of light in the medium), you could then resolve,
In this scenario, the calculated value of refractive index will yield: n = 1.58.
Step 8