With reference to street-lighting, how do sodium lamps differ from LED lamps? 1. Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps. 2. As street-lights, sodium lamps have longer life span than LED lamps. 3. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting. Select the correct answer using the code given below.

The LED symbol shows arrows indicating that an LED emits light, giving a rule-like representation that LEDs produce directed light output.

A student could combine this with knowledge that real LEDs are often packaged with lenses/reflectors to shape those emission arrows into specific beam patterns for streetlights.

States that most visible light sources (except lasers) emit light in various directions, a general pattern about emission spread.

Use this general rule plus knowledge of lamp design (streetlight optics) to suspect that uncontrolled sources tend toward multi-directional emission, so streetlight design must manage that.

Describes an incandescent bulb with a glowing filament viewable from all sides, an example of an essentially omnidirectional lamp.

Compare this with LEDs: if incandescent bulbs emit in many directions, a student could ask whether LEDs (different emitter geometry) are similar or are optically constrained by housings.

Notes that many torches use LED lamps — an example context where LEDs are used with housings/lenses to produce directed beams.

A student could inspect a torch or streetlight: if torch LEDs use reflectors to focus light, streetlight LEDs likely also use optics rather than emitting uniformly.

Demonstrates that light changes direction when reflected by mirrors/plates, highlighting that fixtures and surroundings can redirect emitted light.

Combine this with the fact that streetlight housings and nearby surfaces reflect or block light to infer that even if an LED emits broadly, the net pattern at street level depends on optics and reflection.

Explicit general rule: 'LED lamps ... are ... and last longer than traditional lamps.'

A student could treat sodium street lights as a form of 'traditional' street lamp and compare typical rated lifetimes (manufacturer specs) for sodium vs LED to test the claim.

Summary repeats that LEDs have properties (two terminals, directional current) and are contrasted with incandescent behaviour, reinforcing the text's general favourable framing of LEDs versus older lamp types.

Use the text's contrast between LED and older lamps to motivate checking whether sodium lamps are grouped with those 'older' types and then compare lifetimes from product data.

Gives a failure mechanism for filament-based incandescent lamps (filament breaks → lamp 'fuses'), illustrating why some older lamp types have shorter lifespans.

A student could use this as a pattern (older filament/discrete-failure designs often fail earlier) and then ask whether sodium lamps share similar failure mechanisms or are more like LEDs (solid-state).

Describes incandescent lamp construction (thin filament in glass) and its vulnerability, reinforcing the pattern that older thermal/filament technologies can have limited life.

Apply this pattern to classify street lamp technologies (filament vs discharge vs solid-state) and then seek typical lifetime ranges for each to judge sodium vs LED.

Recommends replacing incandescent bulbs with more energy-efficient types, implying a policy/technical preference for newer, longer‑lasting, efficient lamp technologies.

Treat this as support for the idea that energy-efficient replacements (like LEDs) are preferred; a student could therefore compare energy‑efficiency and lifetime specs of sodium and LED street lights to evaluate the statement.

A prism disperses white light into a continuous band of colours, implying some light sources produce a broad spectrum rather than narrow lines.

A student could compare the prism spectrum of an unknown lamp to that of a broad source: if sodium lamps were nearly monochromatic, a prism would show narrow lines instead of a continuous band.

An incandescent filament 'glows' (thermal emission), which by implication is a broad-spectrum source rather than emission in narrow lines.

Use the incandescent lamp as a contrast example: if sodium streetlights are nearly monochromatic, their prism or spectroscope signature would differ markedly from the filament's continuous glow.

The snippet mentions 'emission of light ... in a low-order manner' and discusses distinct absorption/emission spectra, indicating that emission spectra can be characterized (broad vs shifted/narrow).

A student could apply the concept of distinct emission spectra to expect that a lamp dominated by specific atomic lines (sodium) would show narrow emission features compared with broad absorbers/emitters.

Most sources of visible light emit in various directions and can scatter; this treats light sources generally rather than implying narrow spectral content, suggesting variation among sources.

Recognize that streetlights are a class of sources subject to scattering and reflection; one could test how a source's directional emission and scattering interact with any narrow spectral lines (e.g., observing colour casts at distance).

Atmospheric scattering depends on wavelength (shorter wavelengths scatter more), indicating that spectral composition affects how distant lights appear.

A student could reason that if a sodium lamp is dominated by longer yellow wavelengths (narrow lines), it would be less scattered than blue-rich sources, producing a distinctive colour/visibility pattern at distance.

Says LEDs are modern, brighter light sources and promoted for their advantages, implying different optical performance compared with older lamps.

A student could use this to motivate comparing spectral/colour properties of newer (LED) vs older technologies (e.g., sodium) by looking up their emission spectra or CRI values.

Explains that white light can be split into component colours (dispersion), highlighting that 'colour' of light depends on its spectral composition.

A student can use the concept to reason that a lamp with a broader, continuous spectrum will render colours differently than one with narrow spectral lines, so they should compare spectra to judge CRI.

Defines dispersion and the idea that different wavelengths make up a spectrum, reinforcing that colour rendering depends on which wavelengths are present.

A student could extend this by checking whether LED sources produce a continuous spectrum (many wavelengths) versus sources with limited lines — affecting perceived colour rendering.

Notes that different colours scatter differently (example: red scatters least), showing that human perception of colour depends on wavelength content and propagation.

A student can combine this with knowledge of lamp spectra to predict how ambient conditions and spectral content influence observed colours under different lamps.

Mentions cost and policy-driven deployment of LEDs, implying LEDs are replacing older technologies in practice, which invites comparison of their performance beyond energy (e.g., colour rendering).

A student could follow this policy lead to find technical specs used in procurement (e.g., required CRI) and compare typical LED vs sodium lamp datasheets.