Light and Larger Objects

[Fatespinner]

PRD light spell wrote:

This spell causes a touched object to glow like a torch, shedding normal light in a 20-foot radius, and increasing the light level for an additional 20 feet by one step, up to normal light (darkness becomes dim light, and dim light becomes normal light). In an area of normal or bright light, this spell has no effect. The effect is immobile, but it can be cast on a movable object.

If a caster were to cast light on an object like, say, a 50' length of rope and then that rope were unfurled to it's full length and laid out along a dark hallway or dropped down into a darkened shaft, would it illuminate everything within 20' of any part of the rope? Meaning you essentially get a line 40' wide and 90' long of illumination from one cantrip cast on a 50' rope? What limitation is there? What if you cast it on a cavern wall? Does the entire wall glow? Only 1 5' x 5' section?

I ask because the idea of using a "glow rope" seems pretty damn useful to me and I wonder if it's legal.

[Nightskies]

The illumination would have to come from one point along the rope, caster's choice at the time of casting. Strictly adhere to the 20 foot radius of the spell, per the rules. You couldn't illuminate an entire castle by casting Light on it, just one point, one 20-foot radius. If you wanted the rope to glow, you could do that with Faerie Fire, sure to work if coiled up at casting (GM could rule it won't work on an unraveled rope), but it only lasts 1 min/level instead of 10 and only has the intensity of a candle. But it is not limited to a single area, only a single object.

Faerie Fire:

School evocation [light]; Level druid 1; Domain light 1
Casting Time 1 standard action
Components V, S, DF
Range long (400 ft. + 40 ft./level)
Area creatures and objects within a 5-ft.-radius burst
Duration 1 min./level (D)
Saving Throw none; Spell Resistance yes

DESCRIPTION
A pale glow surrounds and outlines the subjects. Outlined subjects shed light as candles. Creatures outlined by faerie fire take a -20 penalty on all Stealth checks. Outlined creatures do not benefit from the concealment normally provided by darkness (though a 2nd-level or higher magical darkness effect functions normally), blur, displacement, invisibility, or similar effects. The light is too dim to have any special effect on undead or dark-dwelling creatures vulnerable to light.

The faerie fire can be blue, green, or violet, according to your choice at the time of casting. The faerie fire does not cause any harm to the objects or creatures thus outlined.

Candle light:

A candle dimly illuminates a small area, increasing the light level in a 5-foot radius by one step (darkness becomes dim light and dim light becomes normal light).