Legal Metrology (Indian Standard Time) Rules 2026 Notified

The correct answer is 180 days. The Rules were notified by the Department of Consumer Affairs on 27 August 2026 and published in the Official Gazette on 29 August 2026, and the release states that they take effect 180 days from the date of that publication. The gap gives telecommunications networks, financial systems, power grids, transport operators, data centres and government information systems time to synchronise with a traceable source before the legal obligation begins. Options A, B and D are not mentioned anywhere in the release and are offered only as plausible commencement periods, since Indian rules are often brought into force after thirty or ninety days. Note the two dates carefully as well, because notification and Gazette publication fall two days apart, and the 180-day count runs from publication rather than from the day the Rules were signed.

The correct answer is CSIR-National Physical Laboratory. It is India's National Metrology Institute, mandated to set up primary national standards and to disseminate them. It maintains the national atomic time scale, generating IST from an ensemble of atomic clocks together with a primary frequency standard, and keeps that scale traceable to within a few nanoseconds of Coordinated Universal Time, which the International Bureau of Weights and Measures maintains. Under the new Rules the Legal Metrology Department is the regulator and enforcer while CSIR-NPL provides the scientific foundation, so the two roles should be held apart. Options B, C and D are all real national scientific bodies, dealing with astronomy, mapping and weather respectively, but none of them is named in the release and none maintains the national time scale.

The correct answer is five. CSIR-NPL, ISRO and the Legal Metrology Department jointly established secondary timescales at Regional Reference Standard Laboratories in Ahmedabad, Bengaluru, Bhubaneswar, Faridabad and Guwahati. Each of these stays continuously traceable to the IST that CSIR-NPL maintains, which together creates a distributed national architecture for spreading the time. The point of spreading it is resilience: if dissemination depended on a single location, one failure would leave the country without a traceable reference. The five laboratories, along with ISRO's NavIC satellite system and the time dissemination infrastructure of NPL and NIC, add capacity and geographical diversity. Options A, C and D are not supported by the release. A memory aid is that the cities are spread across the west, south, east, north and north-east of the country.

The correct answer is NavIC. CSIR-NPL provides traceability of Indian Standard Time to ISRO for the NavIC system, which allows the time to be spread by satellite and strengthens both the availability and the resilience of national timing services. The release lists NavIC alongside network-based routes such as NTP and PTP, and optical fibre technologies such as White Rabbit that are still under testing. Option A, GAGAN, is an Indian satellite-based augmentation system used mainly to improve navigation accuracy for civil aviation, and it is not named here. Options C and D name the European and Russian global navigation satellite systems, which are foreign systems and have no role in disseminating India's legal time. For examinations, link the three routes to their carriers: NTP and PTP over networks, NavIC by satellite, White Rabbit over fibre.